What is the general solution for cot^2(x)=tan(1/2 x) ?

The general solution for cot^2(x)=tan(1/2 x) is x=2*0.47448…+2pin,x=2*1.34922…+2pin

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cot^2(x)=tan(1/2 x)

Solution

cot^{2} (x) = tan (\frac{1}{2} x)

Solution

x = 2 \cdot 0.47448 \dots + 2 πn, x = 2 \cdot 1.34922 \dots + 2 πn

Degrees

x = 54.37186 \dots^{\circ} + 36 0^{\circ} n, x = 154.60973 \dots^{\circ} + 36 0^{\circ} n

Solution steps

cot^{2} (x) = tan (\frac{1}{2} x)

Subtract

tan (\frac{1}{2} x)

from both sides

cot^{2} (x) - tan (\frac{x}{2}) = 0

Let:

u = \frac{x}{2}

cot^{2} (2 u) - tan (u) = 0

Rewrite using trig identities

cot^{2} (2 u) - tan (u)

Use the basic trigonometric identity:

cot (x) = \frac{1}{tan ( x )}

= (\frac{1}{tan ( 2 u )})^{2} - tan (u)

(\frac{1}{tan ( 2 u )})^{2} = \frac{1}{tan ^{2} ( 2 u )}

(\frac{1}{tan ( 2 u )})^{2}

Apply exponent rule:

(\frac{a}{b})^{c} = \frac{a ^{c}}{b ^{c}}

= \frac{1 ^{2}}{tan ^{2} ( 2 u )}

Apply rule

1^{a} = 1

1^{2} = 1

= \frac{1}{tan ^{2} ( 2 u )}

= \frac{1}{tan ^{2} ( 2 u )} - tan (u)

Use the Double Angle identity:

tan (2 x) = \frac{2 tan ( x )}{1 - tan ^{2} ( x )}

= \frac{1}{( \frac{2 t a n ( u )}{1 - t a n ^{2} ( u )} ) ^{2}} - tan (u)

Simplify

\frac{1}{( \frac{2 t a n ( u )}{1 - t a n ^{2} ( u )} ) ^{2}} - tan (u) : \frac{( 1 - tan ^{2} ( u ) ) ^{2}}{4 tan ^{2} ( u )} - tan (u)

\frac{1}{( \frac{2 t a n ( u )}{1 - t a n ^{2} ( u )} ) ^{2}} - tan (u)

\frac{1}{( \frac{2 t a n ( u )}{1 - t a n ^{2} ( u )} ) ^{2}} = \frac{( 1 - tan ^{2} ( u ) ) ^{2}}{2 ^{2} tan ^{2} ( u )}

\frac{1}{( \frac{2 t a n ( u )}{1 - t a n ^{2} ( u )} ) ^{2}}

(\frac{2 tan ( u )}{1 - tan ^{2} ( u )})^{2} = \frac{2 ^{2} tan ^{2} ( u )}{( 1 - tan ^{2} ( u ) ) ^{2}}

(\frac{2 tan ( u )}{1 - tan ^{2} ( u )})^{2}

Apply exponent rule:

(\frac{a}{b})^{c} = \frac{a ^{c}}{b ^{c}}

= \frac{( 2 tan ( u ) ) ^{2}}{( 1 - tan ^{2} ( u ) ) ^{2}}

Apply exponent rule:

(a \cdot b)^{n} = a^{n} b^{n}

(2 tan (u))^{2} = 2^{2} tan^{2} (u)

= \frac{2 ^{2} tan ^{2} ( u )}{( 1 - tan ^{2} ( u ) ) ^{2}}

= \frac{1}{\frac{2 ^{2} t a n ^{2} ( u )}{( 1 - t a n ^{2} ( u ) ) ^{2}}}

Apply the fraction rule:

\frac{1}{\frac{b}{c}} = \frac{c}{b}

= \frac{( 1 - tan ^{2} ( u ) ) ^{2}}{2 ^{2} tan ^{2} ( u )}

= \frac{( - tan ^{2} ( u ) + 1 ) ^{2}}{2 ^{2} tan ^{2} ( u )} - tan (u)

2^{2} = 4

= \frac{( - tan ^{2} ( u ) + 1 ) ^{2}}{4 tan ^{2} ( u )} - tan (u)

= \frac{( 1 - tan ^{2} ( u ) ) ^{2}}{4 tan ^{2} ( u )} - tan (u)

\frac{( 1 - tan ^{2} ( u ) ) ^{2}}{4 tan ^{2} ( u )} - tan (u) = 0

Solve by substitution

\frac{( 1 - tan ^{2} ( u ) ) ^{2}}{4 tan ^{2} ( u )} - tan (u) = 0

Let:

tan (u) = u

\frac{( 1 - u ^{2} ) ^{2}}{4 u ^{2}} - u = 0

\frac{( 1 - u ^{2} ) ^{2}}{4 u ^{2}} - u = 0 : u \approx 0.51361 \dots, u \approx 4.43910 \dots

\frac{( 1 - u ^{2} ) ^{2}}{4 u ^{2}} - u = 0

Multiply both sides by

4 u^{2}

\frac{( 1 - u ^{2} ) ^{2}}{4 u ^{2}} - u = 0

Multiply both sides by

4 u^{2}

\frac{( 1 - u ^{2} ) ^{2}}{4 u ^{2}} \cdot 4 u^{2} - u \cdot 4 u^{2} = 0 \cdot 4 u^{2}

Simplify

\frac{( 1 - u ^{2} ) ^{2}}{4 u ^{2}} \cdot 4 u^{2} - u \cdot 4 u^{2} = 0 \cdot 4 u^{2}

Simplify

\frac{( 1 - u ^{2} ) ^{2}}{4 u ^{2}} \cdot 4 u^{2} : (1 - u^{2})^{2}

\frac{( 1 - u ^{2} ) ^{2}}{4 u ^{2}} \cdot 4 u^{2}

Multiply fractions:

a \cdot \frac{b}{c} = \frac{a \cdot b}{c}

= \frac{( 1 - u ^{2} ) ^{2} \cdot 4 u ^{2}}{4 u ^{2}}

Cancel the common factor:

4

= \frac{( 1 - u ^{2} ) ^{2} u ^{2}}{u ^{2}}

Cancel the common factor:

u^{2}

= (1 - u^{2})^{2}

Simplify

- u \cdot 4 u^{2} : - 4 u^{3}

- u \cdot 4 u^{2}

Apply exponent rule:

a^{b} \cdot a^{c} = a^{b + c}

u u^{2} = u^{1 + 2}

= - 4 u^{1 + 2}

Add the numbers:

1 + 2 = 3

= - 4 u^{3}

Simplify

0 \cdot 4 u^{2} : 0

0 \cdot 4 u^{2}

Apply rule

0 \cdot a = 0

= 0

(1 - u^{2})^{2} - 4 u^{3} = 0

(1 - u^{2})^{2} - 4 u^{3} = 0

(1 - u^{2})^{2} - 4 u^{3} = 0

Solve

(1 - u^{2})^{2} - 4 u^{3} = 0 : u \approx 0.51361 \dots, u \approx 4.43910 \dots

(1 - u^{2})^{2} - 4 u^{3} = 0

Expand

(1 - u^{2})^{2} - 4 u^{3} : 1 - 2 u^{2} + u^{4} - 4 u^{3}

(1 - u^{2})^{2} - 4 u^{3}

(1 - u^{2})^{2} : 1 - 2 u^{2} + u^{4}

Apply Perfect Square Formula:

(a - b)^{2} = a^{2} - 2 ab + b^{2}

a = 1, b = u^{2}

= 1^{2} - 2 \cdot 1 \cdot u^{2} + (u^{2})^{2}

Simplify

1^{2} - 2 \cdot 1 \cdot u^{2} + (u^{2})^{2} : 1 - 2 u^{2} + u^{4}

1^{2} - 2 \cdot 1 \cdot u^{2} + (u^{2})^{2}

Apply rule

1^{a} = 1

1^{2} = 1

= 1 - 2 \cdot 1 \cdot u^{2} + (u^{2})^{2}

2 \cdot 1 \cdot u^{2} = 2 u^{2}

2 \cdot 1 \cdot u^{2}

Multiply the numbers:

2 \cdot 1 = 2

= 2 u^{2}

(u^{2})^{2} = u^{4}

(u^{2})^{2}

Apply exponent rule:

(a^{b})^{c} = a^{b c}

= u^{2 \cdot 2}

Multiply the numbers:

2 \cdot 2 = 4

= u^{4}

= 1 - 2 u^{2} + u^{4}

= 1 - 2 u^{2} + u^{4}

= 1 - 2 u^{2} + u^{4} - 4 u^{3}

1 - 2 u^{2} + u^{4} - 4 u^{3} = 0

Write in the standard form

a_{n} x^{n} + \dots + a_{1} x + a_{0} = 0

u^{4} - 4 u^{3} - 2 u^{2} + 1 = 0

Find one solution for

u^{4} - 4 u^{3} - 2 u^{2} + 1 = 0

using Newton-Raphson:

u \approx 0.51361 \dots

u^{4} - 4 u^{3} - 2 u^{2} + 1 = 0

Newton-Raphson Approximation Definition

f (u) = u^{4} - 4 u^{3} - 2 u^{2} + 1

Find

f^{^{'}} (u) : 4 u^{3} - 12 u^{2} - 4 u

\frac{d}{d u} (u^{4} - 4 u^{3} - 2 u^{2} + 1)

Apply the Sum/Difference Rule:

(f \pm g)^{'} = f^{'} \pm g^{'}

= \frac{d}{d u} (u^{4}) - \frac{d}{d u} (4 u^{3}) - \frac{d}{d u} (2 u^{2}) + \frac{d}{d u} (1)

\frac{d}{d u} (u^{4}) = 4 u^{3}

\frac{d}{d u} (u^{4})

Apply the Power Rule:

\frac{d}{d x} (x^{a}) = a \cdot x^{a - 1}

= 4 u^{4 - 1}

Simplify

= 4 u^{3}

\frac{d}{d u} (4 u^{3}) = 12 u^{2}

\frac{d}{d u} (4 u^{3})

Take the constant out:

(a \cdot f)^{'} = a \cdot f^{'}

= 4 \frac{d}{d u} (u^{3})

Apply the Power Rule:

\frac{d}{d x} (x^{a}) = a \cdot x^{a - 1}

= 4 \cdot 3 u^{3 - 1}

Simplify

= 12 u^{2}

\frac{d}{d u} (2 u^{2}) = 4 u

\frac{d}{d u} (2 u^{2})

Take the constant out:

(a \cdot f)^{'} = a \cdot f^{'}

= 2 \frac{d}{d u} (u^{2})

Apply the Power Rule:

\frac{d}{d x} (x^{a}) = a \cdot x^{a - 1}

= 2 \cdot 2 u^{2 - 1}

Simplify

= 4 u

\frac{d}{d u} (1) = 0

\frac{d}{d u} (1)

Derivative of a constant:

\frac{d}{d x} (a) = 0

= 0

= 4 u^{3} - 12 u^{2} - 4 u + 0

Simplify

= 4 u^{3} - 12 u^{2} - 4 u

Let

u_{0} = 1

Compute

u_{n + 1}

until

Δ u_{n + 1} < 0.000001

u_{1} = 0.66666 \dots : Δ u_{1} = 0.33333 \dots

f (u_{0}) = 1^{4} - 4 \cdot 1^{3} - 2 \cdot 1^{2} + 1 = - 4

f^{^{'}} (u_{0}) = 4 \cdot 1^{3} - 12 \cdot 1^{2} - 4 \cdot 1 = - 12

u_{1} = 0.66666 \dots

Δ u_{1} = ∣ 0.66666 \dots - 1 ∣ = 0.33333 \dots

Δ u_{1} = 0.33333 \dots

u_{2} = 0.53804 \dots : Δ u_{2} = 0.12862 \dots

f (u_{1}) = 0.66666 \dots^{4} - 4 \cdot 0.66666 \dots^{3} - 2 \cdot 0.66666 \dots^{2} + 1 = - 0.87654 \dots

f^{^{'}} (u_{1}) = 4 \cdot 0.66666 \dots^{3} - 12 \cdot 0.66666 \dots^{2} - 4 \cdot 0.66666 \dots = - 6.81481 \dots

u_{2} = 0.53804 \dots

Δ u_{2} = ∣ 0.53804 \dots - 0.66666 \dots ∣ = 0.12862 \dots

Δ u_{2} = 0.12862 \dots

u_{3} = 0.51441 \dots : Δ u_{3} = 0.02362 \dots

f (u_{2}) = 0.53804 \dots^{4} - 4 \cdot 0.53804 \dots^{3} - 2 \cdot 0.53804 \dots^{2} + 1 = - 0.11821 \dots

f^{^{'}} (u_{2}) = 4 \cdot 0.53804 \dots^{3} - 12 \cdot 0.53804 \dots^{2} - 4 \cdot 0.53804 \dots = - 5.00302 \dots

u_{3} = 0.51441 \dots

Δ u_{3} = ∣ 0.51441 \dots - 0.53804 \dots ∣ = 0.02362 \dots

Δ u_{3} = 0.02362 \dots

u_{4} = 0.51362 \dots : Δ u_{4} = 0.00079 \dots

f (u_{3}) = 0.51441 \dots^{4} - 4 \cdot 0.51441 \dots^{3} - 2 \cdot 0.51441 \dots^{2} + 1 = - 0.00372 \dots

f^{^{'}} (u_{3}) = 4 \cdot 0.51441 \dots^{3} - 12 \cdot 0.51441 \dots^{2} - 4 \cdot 0.51441 \dots = - 4.68863 \dots

u_{4} = 0.51362 \dots

Δ u_{4} = ∣ 0.51362 \dots - 0.51441 \dots ∣ = 0.00079 \dots

Δ u_{4} = 0.00079 \dots

u_{5} = 0.51361 \dots : Δ u_{5} = 8.89103 E - 7

f (u_{4}) = 0.51362 \dots^{4} - 4 \cdot 0.51362 \dots^{3} - 2 \cdot 0.51362 \dots^{2} + 1 = - 4.15938 E - 6

f^{^{'}} (u_{4}) = 4 \cdot 0.51362 \dots^{3} - 12 \cdot 0.51362 \dots^{2} - 4 \cdot 0.51362 \dots = - 4.67817 \dots

u_{5} = 0.51361 \dots

Δ u_{5} = ∣ 0.51361 \dots - 0.51362 \dots ∣ = 8.89103 E - 7

Δ u_{5} = 8.89103 E - 7

u \approx 0.51361 \dots

Apply long division:

\frac{u ^{4} - 4 u ^{3} - 2 u ^{2} + 1}{u - 0.51361 \dots} = u^{3} - 3.48638 \dots u^{2} - 3.79067 \dots u - 1.94696 \dots

u^{3} - 3.48638 \dots u^{2} - 3.79067 \dots u - 1.94696 \dots \approx 0

Find one solution for

u^{3} - 3.48638 \dots u^{2} - 3.79067 \dots u - 1.94696 \dots = 0

using Newton-Raphson:

u \approx 4.43910 \dots

u^{3} - 3.48638 \dots u^{2} - 3.79067 \dots u - 1.94696 \dots = 0

Newton-Raphson Approximation Definition

f (u) = u^{3} - 3.48638 \dots u^{2} - 3.79067 \dots u - 1.94696 \dots

Find

f^{^{'}} (u) : 3 u^{2} - 6.97276 \dots u - 3.79067 \dots

\frac{d}{d u} (u^{3} - 3.48638 \dots u^{2} - 3.79067 \dots u - 1.94696 \dots)

Apply the Sum/Difference Rule:

(f \pm g)^{'} = f^{'} \pm g^{'}

= \frac{d}{d u} (u^{3}) - \frac{d}{d u} (3.48638 \dots u^{2}) - \frac{d}{d u} (3.79067 \dots u) - \frac{d}{d u} (1.94696 \dots)

\frac{d}{d u} (u^{3}) = 3 u^{2}

\frac{d}{d u} (u^{3})

Apply the Power Rule:

\frac{d}{d x} (x^{a}) = a \cdot x^{a - 1}

= 3 u^{3 - 1}

Simplify

= 3 u^{2}

\frac{d}{d u} (3.48638 \dots u^{2}) = 6.97276 \dots u

\frac{d}{d u} (3.48638 \dots u^{2})

Take the constant out:

(a \cdot f)^{'} = a \cdot f^{'}

= 3.48638 \dots \frac{d}{d u} (u^{2})

Apply the Power Rule:

\frac{d}{d x} (x^{a}) = a \cdot x^{a - 1}

= 3.48638 \dots \cdot 2 u^{2 - 1}

Simplify

= 6.97276 \dots u

\frac{d}{d u} (3.79067 \dots u) = 3.79067 \dots

\frac{d}{d u} (3.79067 \dots u)

Take the constant out:

(a \cdot f)^{'} = a \cdot f^{'}

= 3.79067 \dots \frac{d u}{d u}

Apply the common derivative:

\frac{d u}{d u} = 1

= 3.79067 \dots \cdot 1

Simplify

= 3.79067 \dots

\frac{d}{d u} (1.94696 \dots) = 0

\frac{d}{d u} (1.94696 \dots)

Derivative of a constant:

\frac{d}{d x} (a) = 0

= 0

= 3 u^{2} - 6.97276 \dots u - 3.79067 \dots - 0

Simplify

= 3 u^{2} - 6.97276 \dots u - 3.79067 \dots

Let

u_{0} = 4

Compute

u_{n + 1}

until

Δ u_{n + 1} < 0.000001

u_{1} = 4.54489 \dots : Δ u_{1} = 0.54489 \dots

f (u_{0}) = 4^{3} - 3.48638 \dots \cdot 4^{2} - 3.79067 \dots \cdot 4 - 1.94696 \dots = - 8.89174 \dots

f^{^{'}} (u_{0}) = 3 \cdot 4^{2} - 6.97276 \dots \cdot 4 - 3.79067 \dots = 16.31828 \dots

u_{1} = 4.54489 \dots

Δ u_{1} = ∣ 4.54489 \dots - 4 ∣ = 0.54489 \dots

Δ u_{1} = 0.54489 \dots

u_{2} = 4.44335 \dots : Δ u_{2} = 0.10154 \dots

f (u_{1}) = 4.54489 \dots^{3} - 3.48638 \dots \cdot 4.54489 \dots^{2} - 3.79067 \dots \cdot 4.54489 \dots - 1.94696 \dots = 2.68956 \dots

f^{^{'}} (u_{1}) = 3 \cdot 4.54489 \dots^{2} - 6.97276 \dots \cdot 4.54489 \dots - 3.79067 \dots = 26.48706 \dots

u_{2} = 4.44335 \dots

Δ u_{2} = ∣ 4.44335 \dots - 4.54489 \dots ∣ = 0.10154 \dots

Δ u_{2} = 0.10154 \dots

u_{3} = 4.43911 \dots : Δ u_{3} = 0.00423 \dots

f (u_{2}) = 4.44335 \dots^{3} - 3.48638 \dots \cdot 4.44335 \dots^{2} - 3.79067 \dots \cdot 4.44335 \dots - 1.94696 \dots = 0.10359 \dots

f^{^{'}} (u_{2}) = 3 \cdot 4.44335 \dots^{2} - 6.97276 \dots \cdot 4.44335 \dots - 3.79067 \dots = 24.45702 \dots

u_{3} = 4.43911 \dots

Δ u_{3} = ∣ 4.43911 \dots - 4.44335 \dots ∣ = 0.00423 \dots

Δ u_{3} = 0.00423 \dots

u_{4} = 4.43910 \dots : Δ u_{4} = 7.24246 E - 6

f (u_{3}) = 4.43911 \dots^{3} - 3.48638 \dots \cdot 4.43911 \dots^{2} - 3.79067 \dots \cdot 4.43911 \dots - 1.94696 \dots = 0.00017 \dots

f^{^{'}} (u_{3}) = 3 \cdot 4.43911 \dots^{2} - 6.97276 \dots \cdot 4.43911 \dots - 3.79067 \dots = 24.37369 \dots

u_{4} = 4.43910 \dots

Δ u_{4} = ∣ 4.43910 \dots - 4.43911 \dots ∣ = 7.24246 E - 6

Δ u_{4} = 7.24246 E - 6

u_{5} = 4.43910 \dots : Δ u_{5} = 2.11568 E - 11

f (u_{4}) = 4.43910 \dots^{3} - 3.48638 \dots \cdot 4.43910 \dots^{2} - 3.79067 \dots \cdot 4.43910 \dots - 1.94696 \dots = 5.15667 E - 10

f^{^{'}} (u_{4}) = 3 \cdot 4.43910 \dots^{2} - 6.97276 \dots \cdot 4.43910 \dots - 3.79067 \dots = 24.37355 \dots

u_{5} = 4.43910 \dots

Δ u_{5} = ∣ 4.43910 \dots - 4.43910 \dots ∣ = 2.11568 E - 11

Δ u_{5} = 2.11568 E - 11

u \approx 4.43910 \dots

Apply long division:

\frac{u ^{3} - 3.48638 \dots u ^{2} - 3.79067 \dots u - 1.94696 \dots}{u - 4.43910 \dots} = u^{2} + 0.95272 \dots u + 0.43859 \dots

u^{2} + 0.95272 \dots u + 0.43859 \dots \approx 0

Find one solution for

u^{2} + 0.95272 \dots u + 0.43859 \dots = 0

using Newton-Raphson:

No Solution for

u \in R

u^{2} + 0.95272 \dots u + 0.43859 \dots = 0

Newton-Raphson Approximation Definition

f (u) = u^{2} + 0.95272 \dots u + 0.43859 \dots

Find

f^{^{'}} (u) : 2 u + 0.95272 \dots

\frac{d}{d u} (u^{2} + 0.95272 \dots u + 0.43859 \dots)

Apply the Sum/Difference Rule:

(f \pm g)^{'} = f^{'} \pm g^{'}

= \frac{d}{d u} (u^{2}) + \frac{d}{d u} (0.95272 \dots u) + \frac{d}{d u} (0.43859 \dots)

\frac{d}{d u} (u^{2}) = 2 u

\frac{d}{d u} (u^{2})

Apply the Power Rule:

\frac{d}{d x} (x^{a}) = a \cdot x^{a - 1}

= 2 u^{2 - 1}

Simplify

= 2 u

\frac{d}{d u} (0.95272 \dots u) = 0.95272 \dots

\frac{d}{d u} (0.95272 \dots u)

Take the constant out:

(a \cdot f)^{'} = a \cdot f^{'}

= 0.95272 \dots \frac{d u}{d u}

Apply the common derivative:

\frac{d u}{d u} = 1

= 0.95272 \dots \cdot 1

Simplify

= 0.95272 \dots

\frac{d}{d u} (0.43859 \dots) = 0

\frac{d}{d u} (0.43859 \dots)

Derivative of a constant:

\frac{d}{d x} (a) = 0

= 0

= 2 u + 0.95272 \dots + 0

Simplify

= 2 u + 0.95272 \dots

Let

u_{0} = 0

Compute

u_{n + 1}

until

Δ u_{n + 1} < 0.000001

u_{1} = - 0.46035 \dots : Δ u_{1} = 0.46035 \dots

f (u_{0}) = 0^{2} + 0.95272 \dots \cdot 0 + 0.43859 \dots = 0.43859 \dots

f^{^{'}} (u_{0}) = 2 \cdot 0 + 0.95272 \dots = 0.95272 \dots

u_{1} = - 0.46035 \dots

Δ u_{1} = ∣ - 0.46035 \dots - 0 ∣ = 0.46035 \dots

Δ u_{1} = 0.46035 \dots

u_{2} = - 7.07923 \dots : Δ u_{2} = 6.61887 \dots

f (u_{1}) = (- 0.46035 \dots)^{2} + 0.95272 \dots (- 0.46035 \dots) + 0.43859 \dots = 0.21192 \dots

f^{^{'}} (u_{1}) = 2 (- 0.46035 \dots) + 0.95272 \dots = 0.03201 \dots

u_{2} = - 7.07923 \dots

Δ u_{2} = ∣ - 7.07923 \dots - (- 0.46035 \dots) ∣ = 6.61887 \dots

Δ u_{2} = 6.61887 \dots

u_{3} = - 3.76176 \dots : Δ u_{3} = 3.31746 \dots

f (u_{2}) = (- 7.07923 \dots)^{2} + 0.95272 \dots (- 7.07923 \dots) + 0.43859 \dots = 43.80952 \dots

f^{^{'}} (u_{2}) = 2 (- 7.07923 \dots) + 0.95272 \dots = - 13.20573 \dots

u_{3} = - 3.76176 \dots

Δ u_{3} = ∣ - 3.76176 \dots - (- 7.07923 \dots) ∣ = 3.31746 \dots

Δ u_{3} = 3.31746 \dots

u_{4} = - 2.08685 \dots : Δ u_{4} = 1.67491 \dots

f (u_{3}) = (- 3.76176 \dots)^{2} + 0.95272 \dots (- 3.76176 \dots) + 0.43859 \dots = 11.00555 \dots

f^{^{'}} (u_{3}) = 2 (- 3.76176 \dots) + 0.95272 \dots = - 6.57081 \dots

u_{4} = - 2.08685 \dots

Δ u_{4} = ∣ - 2.08685 \dots - (- 3.76176 \dots) ∣ = 1.67491 \dots

Δ u_{4} = 1.67491 \dots

u_{5} = - 1.21589 \dots : Δ u_{5} = 0.87096 \dots

f (u_{4}) = (- 2.08685 \dots)^{2} + 0.95272 \dots (- 2.08685 \dots) + 0.43859 \dots = 2.80534 \dots

f^{^{'}} (u_{4}) = 2 (- 2.08685 \dots) + 0.95272 \dots = - 3.22097 \dots

u_{5} = - 1.21589 \dots

Δ u_{5} = ∣ - 1.21589 \dots - (- 2.08685 \dots) ∣ = 0.87096 \dots

Δ u_{5} = 0.87096 \dots

u_{6} = - 0.70301 \dots : Δ u_{6} = 0.51287 \dots

f (u_{5}) = (- 1.21589 \dots)^{2} + 0.95272 \dots (- 1.21589 \dots) + 0.43859 \dots = 0.75857 \dots

f^{^{'}} (u_{5}) = 2 (- 1.21589 \dots) + 0.95272 \dots = - 1.47905 \dots

u_{6} = - 0.70301 \dots

Δ u_{6} = ∣ - 0.70301 \dots - (- 1.21589 \dots) ∣ = 0.51287 \dots

Δ u_{6} = 0.51287 \dots

u_{7} = - 0.12274 \dots : Δ u_{7} = 0.58027 \dots

f (u_{6}) = (- 0.70301 \dots)^{2} + 0.95272 \dots (- 0.70301 \dots) + 0.43859 \dots = 0.26304 \dots

f^{^{'}} (u_{6}) = 2 (- 0.70301 \dots) + 0.95272 \dots = - 0.45330 \dots

u_{7} = - 0.12274 \dots

Δ u_{7} = ∣ - 0.12274 \dots - (- 0.70301 \dots) ∣ = 0.58027 \dots

Δ u_{7} = 0.58027 \dots

u_{8} = - 0.59883 \dots : Δ u_{8} = 0.47609 \dots

f (u_{7}) = (- 0.12274 \dots)^{2} + 0.95272 \dots (- 0.12274 \dots) + 0.43859 \dots = 0.33672 \dots

f^{^{'}} (u_{7}) = 2 (- 0.12274 \dots) + 0.95272 \dots = 0.70724 \dots

u_{8} = - 0.59883 \dots

Δ u_{8} = ∣ - 0.59883 \dots - (- 0.12274 \dots) ∣ = 0.47609 \dots

Δ u_{8} = 0.47609 \dots

u_{9} = 0.32653 \dots : Δ u_{9} = 0.92537 \dots

f (u_{8}) = (- 0.59883 \dots)^{2} + 0.95272 \dots (- 0.59883 \dots) + 0.43859 \dots = 0.22667 \dots

f^{^{'}} (u_{8}) = 2 (- 0.59883 \dots) + 0.95272 \dots = - 0.24495 \dots

u_{9} = 0.32653 \dots

Δ u_{9} = ∣ 0.32653 \dots - (- 0.59883 \dots) ∣ = 0.92537 \dots

Δ u_{9} = 0.92537 \dots

u_{10} = - 0.20673 \dots : Δ u_{10} = 0.53326 \dots

f (u_{9}) = 0.32653 \dots^{2} + 0.95272 \dots \cdot 0.32653 \dots + 0.43859 \dots = 0.85631 \dots

f^{^{'}} (u_{9}) = 2 \cdot 0.32653 \dots + 0.95272 \dots = 1.60579 \dots

u_{10} = - 0.20673 \dots

Δ u_{10} = ∣ - 0.20673 \dots - 0.32653 \dots ∣ = 0.53326 \dots

Δ u_{10} = 0.53326 \dots

u_{11} = - 0.73406 \dots : Δ u_{11} = 0.52733 \dots

f (u_{10}) = (- 0.20673 \dots)^{2} + 0.95272 \dots (- 0.20673 \dots) + 0.43859 \dots = 0.28437 \dots

f^{^{'}} (u_{10}) = 2 (- 0.20673 \dots) + 0.95272 \dots = 0.53926 \dots

u_{11} = - 0.73406 \dots

Δ u_{11} = ∣ - 0.73406 \dots - (- 0.20673 \dots) ∣ = 0.52733 \dots

Δ u_{11} = 0.52733 \dots

u_{12} = - 0.19452 \dots : Δ u_{12} = 0.53954 \dots

f (u_{11}) = (- 0.73406 \dots)^{2} + 0.95272 \dots (- 0.73406 \dots) + 0.43859 \dots = 0.27807 \dots

f^{^{'}} (u_{11}) = 2 (- 0.73406 \dots) + 0.95272 \dots = - 0.51539 \dots

u_{12} = - 0.19452 \dots

Δ u_{12} = ∣ - 0.19452 \dots - (- 0.73406 \dots) ∣ = 0.53954 \dots

Δ u_{12} = 0.53954 \dots

Cannot find solution

The solutions are

u \approx 0.51361 \dots, u \approx 4.43910 \dots

u \approx 0.51361 \dots, u \approx 4.43910 \dots

Verify Solutions

Find undefined (singularity) points:

u = 0

Take the denominator(s) of

\frac{( 1 - u ^{2} ) ^{2}}{4 u ^{2}} - u

and compare to zero

Solve

4 u^{2} = 0 : u = 0

4 u^{2} = 0

Divide both sides by

4

4 u^{2} = 0

Divide both sides by

4

4 u^{2} = 0

Divide both sides by

4

\frac{4 u ^{2}}{4} = \frac{0}{4}

Simplify

u^{2} = 0

u^{2} = 0

Apply rule

x^{n} = 0 \Rightarrow x = 0

u = 0

The following points are undefined

u = 0

Combine undefined points with solutions:

u \approx 0.51361 \dots, u \approx 4.43910 \dots

Substitute back

u = tan (u)

tan (u) \approx 0.51361 \dots, tan (u) \approx 4.43910 \dots

tan (u) \approx 0.51361 \dots, tan (u) \approx 4.43910 \dots

tan (u) = 0.51361 \dots : u = arctan (0.51361 \dots) + πn

tan (u) = 0.51361 \dots

Apply trig inverse properties

tan (u) = 0.51361 \dots

General solutions for

tan (u) = 0.51361 \dots

tan (x) = a \Rightarrow x = arctan (a) + πn

u = arctan (0.51361 \dots) + πn

u = arctan (0.51361 \dots) + πn

tan (u) = 4.43910 \dots : u = arctan (4.43910 \dots) + πn

tan (u) = 4.43910 \dots

Apply trig inverse properties

tan (u) = 4.43910 \dots

General solutions for

tan (u) = 4.43910 \dots

tan (x) = a \Rightarrow x = arctan (a) + πn

u = arctan (4.43910 \dots) + πn

u = arctan (4.43910 \dots) + πn

Combine all the solutions

u = arctan (0.51361 \dots) + πn, u = arctan (4.43910 \dots) + πn

Substitute back

u = \frac{x}{2}

\frac{x}{2} = arctan (0.51361 \dots) + πn : x = 2 arctan (0.51361 \dots) + 2 πn

\frac{x}{2} = arctan (0.51361 \dots) + πn

Multiply both sides by

2

\frac{x}{2} = arctan (0.51361 \dots) + πn

Multiply both sides by

2

\frac{2 x}{2} = 2 arctan (0.51361 \dots) + 2 πn

Simplify

x = 2 arctan (0.51361 \dots) + 2 πn

x = 2 arctan (0.51361 \dots) + 2 πn

\frac{x}{2} = arctan (4.43910 \dots) + πn : x = 2 arctan (4.43910 \dots) + 2 πn

\frac{x}{2} = arctan (4.43910 \dots) + πn

Multiply both sides by

2

\frac{x}{2} = arctan (4.43910 \dots) + πn

Multiply both sides by

2

\frac{2 x}{2} = 2 arctan (4.43910 \dots) + 2 πn

Simplify

x = 2 arctan (4.43910 \dots) + 2 πn

x = 2 arctan (4.43910 \dots) + 2 πn

x = 2 arctan (0.51361 \dots) + 2 πn, x = 2 arctan (4.43910 \dots) + 2 πn

Show solutions in decimal form

x = 2 \cdot 0.47448 \dots + 2 πn, x = 2 \cdot 1.34922 \dots + 2 πn

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Frequently Asked Questions (FAQ)

What is the general solution for cot^2(x)=tan(1/2 x) ?
The general solution for cot^2(x)=tan(1/2 x) is x=2*0.47448…+2pin,x=2*1.34922…+2pin