What is the general solution for sin(θ)=cos(2θ+60) ?

The general solution for sin(θ)=cos(2θ+60) is θ=(2160n+180}{18},θ=-\frac{900+2160n)/6

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Popular Trigonometry >

sin(θ)=cos(2θ+60)

Solution

sin (θ) = cos (2 θ + 6 0^{\circ})

Solution

θ = \frac{216 0 ^{\circ} n + 18 0 ^{\circ}}{18}, θ = - \frac{90 0 ^{\circ} + 216 0 ^{\circ} n}{6}

Radians

θ = \frac{π}{18} + \frac{12 π}{18} n, θ = - \frac{5 π}{6} - \frac{12 π}{6} n

Solution steps

sin (θ) = cos (2 θ + 6 0^{\circ})

Rewrite using trig identities

sin (θ) = cos (2 θ + 6 0^{\circ})

Use the following identity:

cos (x) = sin (9 0^{\circ} - x)

sin (θ) = sin (9 0^{\circ} - (2 θ + 6 0^{\circ}))

sin (θ) = sin (9 0^{\circ} - (2 θ + 6 0^{\circ}))

Apply trig inverse properties

sin (θ) = sin (9 0^{\circ} - (2 θ + 6 0^{\circ}))

sin (x) = sin (y) \Rightarrow x = y + 2 π n, x = π - y + 2 π n

θ = 9 0^{\circ} - (2 θ + 6 0^{\circ}) + 36 0^{\circ} n, θ = 18 0^{\circ} - (9 0^{\circ} - (2 θ + 6 0^{\circ})) + 36 0^{\circ} n

θ = 9 0^{\circ} - (2 θ + 6 0^{\circ}) + 36 0^{\circ} n, θ = 18 0^{\circ} - (9 0^{\circ} - (2 θ + 6 0^{\circ})) + 36 0^{\circ} n

θ = 9 0^{\circ} - (2 θ + 6 0^{\circ}) + 36 0^{\circ} n : θ = \frac{216 0 ^{\circ} n + 18 0 ^{\circ}}{18}

θ = 9 0^{\circ} - (2 θ + 6 0^{\circ}) + 36 0^{\circ} n

Expand

9 0^{\circ} - (2 θ + 6 0^{\circ}) + 36 0^{\circ} n : - 2 θ + 36 0^{\circ} n + 3 0^{\circ}

9 0^{\circ} - (2 θ + 6 0^{\circ}) + 36 0^{\circ} n

- (2 θ + 6 0^{\circ}) : - 2 θ - 6 0^{\circ}

- (2 θ + 6 0^{\circ})

Distribute parentheses

= - (2 θ) - (6 0^{\circ})

Apply minus-plus rules

+ (- a) = - a

= - 2 θ - 6 0^{\circ}

= 9 0^{\circ} - 2 θ - 6 0^{\circ} + 36 0^{\circ} n

Simplify

9 0^{\circ} - 2 θ - 6 0^{\circ} + 36 0^{\circ} n : - 2 θ + 36 0^{\circ} n + 3 0^{\circ}

9 0^{\circ} - 2 θ - 6 0^{\circ} + 36 0^{\circ} n

Group like terms

= - 2 θ + 36 0^{\circ} n + 9 0^{\circ} - 6 0^{\circ}

Least Common Multiplier of

2, 3 : 6

2, 3

Least Common Multiplier (LCM)

Prime factorization of

2 : 2

2

2

is a prime number, therefore no factorization is possible

= 2

Prime factorization of

3 : 3

3

3

is a prime number, therefore no factorization is possible

= 3

Multiply each factor the greatest number of times it occurs in either

2

3

= 2 \cdot 3

Multiply the numbers:

2 \cdot 3 = 6

= 6

Adjust Fractions based on the LCM

Multiply each numerator by the same amount needed to multiply its

corresponding denominator to turn it into the LCM

6

For

9 0^{\circ} :

multiply the denominator and numerator by

3

9 0^{\circ} = \frac{18 0 ^{\circ} 3}{2 \cdot 3} = 9 0^{\circ}

For

6 0^{\circ} :

multiply the denominator and numerator by

2

6 0^{\circ} = \frac{18 0 ^{\circ} 2}{3 \cdot 2} = 6 0^{\circ}

= 9 0^{\circ} - 6 0^{\circ}

Since the denominators are equal, combine the fractions:

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

= \frac{18 0 ^{\circ} 3 - 18 0 ^{\circ} 2}{6}

Add similar elements:

54 0^{\circ} - 36 0^{\circ} = 18 0^{\circ}

= - 2 θ + 36 0^{\circ} n + 3 0^{\circ}

= - 2 θ + 36 0^{\circ} n + 3 0^{\circ}

θ = - 2 θ + 36 0^{\circ} n + 3 0^{\circ}

Move

2 θ

to the left side

θ = - 2 θ + 36 0^{\circ} n + 3 0^{\circ}

Add

2 θ

to both sides

θ + 2 θ = - 2 θ + 36 0^{\circ} n + 3 0^{\circ} + 2 θ

Simplify

3 θ = 36 0^{\circ} n + 3 0^{\circ}

3 θ = 36 0^{\circ} n + 3 0^{\circ}

Divide both sides by

3

3 θ = 36 0^{\circ} n + 3 0^{\circ}

Divide both sides by

3

\frac{3 θ}{3} = \frac{36 0 ^{\circ} n}{3} + \frac{3 0 ^{\circ}}{3}

Simplify

\frac{3 θ}{3} = \frac{36 0 ^{\circ} n}{3} + \frac{3 0 ^{\circ}}{3}

Simplify

\frac{3 θ}{3} : θ

\frac{3 θ}{3}

Divide the numbers:

\frac{3}{3} = 1

= θ

Simplify

\frac{36 0 ^{\circ} n}{3} + \frac{3 0 ^{\circ}}{3} : \frac{216 0 ^{\circ} n + 18 0 ^{\circ}}{18}

\frac{36 0 ^{\circ} n}{3} + \frac{3 0 ^{\circ}}{3}

Apply rule

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

= \frac{36 0 ^{\circ} n + 3 0 ^{\circ}}{3}

Join

36 0^{\circ} n + 3 0^{\circ} : \frac{216 0 ^{\circ} n + 18 0 ^{\circ}}{6}

36 0^{\circ} n + 3 0^{\circ}

Convert element to fraction:

36 0^{\circ} n = \frac{36 0 ^{\circ} n 6}{6}

= \frac{36 0 ^{\circ} n \cdot 6}{6} + 3 0^{\circ}

Since the denominators are equal, combine the fractions:

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

= \frac{36 0 ^{\circ} n \cdot 6 + 18 0 ^{\circ}}{6}

Multiply the numbers:

2 \cdot 6 = 12

= \frac{216 0 ^{\circ} n + 18 0 ^{\circ}}{6}

= \frac{\frac{216 0 ^{\circ} n + 18 0 ^{\circ}}{6}}{3}

Apply the fraction rule:

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

= \frac{216 0 ^{\circ} n + 18 0 ^{\circ}}{6 \cdot 3}

Multiply the numbers:

6 \cdot 3 = 18

= \frac{216 0 ^{\circ} n + 18 0 ^{\circ}}{18}

θ = \frac{216 0 ^{\circ} n + 18 0 ^{\circ}}{18}

θ = \frac{216 0 ^{\circ} n + 18 0 ^{\circ}}{18}

θ = \frac{216 0 ^{\circ} n + 18 0 ^{\circ}}{18}

θ = 18 0^{\circ} - (9 0^{\circ} - (2 θ + 6 0^{\circ})) + 36 0^{\circ} n : θ = - \frac{90 0 ^{\circ} + 216 0 ^{\circ} n}{6}

θ = 18 0^{\circ} - (9 0^{\circ} - (2 θ + 6 0^{\circ})) + 36 0^{\circ} n

Expand

18 0^{\circ} - (9 0^{\circ} - (2 θ + 6 0^{\circ})) + 36 0^{\circ} n : 18 0^{\circ} + 2 θ - 3 0^{\circ} + 36 0^{\circ} n

18 0^{\circ} - (9 0^{\circ} - (2 θ + 6 0^{\circ})) + 36 0^{\circ} n

Expand

9 0^{\circ} - (2 θ + 6 0^{\circ}) : - 2 θ + 3 0^{\circ}

9 0^{\circ} - (2 θ + 6 0^{\circ})

- (2 θ + 6 0^{\circ}) : - 2 θ - 6 0^{\circ}

- (2 θ + 6 0^{\circ})

Distribute parentheses

= - (2 θ) - (6 0^{\circ})

Apply minus-plus rules

+ (- a) = - a

= - 2 θ - 6 0^{\circ}

= 9 0^{\circ} - 2 θ - 6 0^{\circ}

Simplify

9 0^{\circ} - 2 θ - 6 0^{\circ} : - 2 θ + 3 0^{\circ}

9 0^{\circ} - 2 θ - 6 0^{\circ}

Group like terms

= - 2 θ + 9 0^{\circ} - 6 0^{\circ}

Least Common Multiplier of

2, 3 : 6

2, 3

Least Common Multiplier (LCM)

Prime factorization of

2 : 2

2

2

is a prime number, therefore no factorization is possible

= 2

Prime factorization of

3 : 3

3

3

is a prime number, therefore no factorization is possible

= 3

Multiply each factor the greatest number of times it occurs in either

2

3

= 2 \cdot 3

Multiply the numbers:

2 \cdot 3 = 6

= 6

Adjust Fractions based on the LCM

Multiply each numerator by the same amount needed to multiply its

corresponding denominator to turn it into the LCM

6

For

9 0^{\circ} :

multiply the denominator and numerator by

3

9 0^{\circ} = \frac{18 0 ^{\circ} 3}{2 \cdot 3} = 9 0^{\circ}

For

6 0^{\circ} :

multiply the denominator and numerator by

2

6 0^{\circ} = \frac{18 0 ^{\circ} 2}{3 \cdot 2} = 6 0^{\circ}

= 9 0^{\circ} - 6 0^{\circ}

Since the denominators are equal, combine the fractions:

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

= \frac{18 0 ^{\circ} 3 - 18 0 ^{\circ} 2}{6}

Add similar elements:

54 0^{\circ} - 36 0^{\circ} = 18 0^{\circ}

= - 2 θ + 3 0^{\circ}

= - 2 θ + 3 0^{\circ}

= 18 0^{\circ} - (- 2 θ + 3 0^{\circ}) + 36 0^{\circ} n

- (- 2 θ + 3 0^{\circ}) : 2 θ - 3 0^{\circ}

- (- 2 θ + 3 0^{\circ})

Distribute parentheses

= - (- 2 θ) - (3 0^{\circ})

Apply minus-plus rules

- (- a) = a, - (a) = - a

= 2 θ - 3 0^{\circ}

= 18 0^{\circ} + 2 θ - 3 0^{\circ} + 36 0^{\circ} n

θ = 18 0^{\circ} + 2 θ - 3 0^{\circ} + 36 0^{\circ} n

Move

2 θ

to the left side

θ = 18 0^{\circ} + 2 θ - 3 0^{\circ} + 36 0^{\circ} n

Subtract

2 θ

from both sides

θ - 2 θ = 18 0^{\circ} + 2 θ - 3 0^{\circ} + 36 0^{\circ} n - 2 θ

Simplify

- θ = 18 0^{\circ} - 3 0^{\circ} + 36 0^{\circ} n

- θ = 18 0^{\circ} - 3 0^{\circ} + 36 0^{\circ} n

Divide both sides by

- 1

- θ = 18 0^{\circ} - 3 0^{\circ} + 36 0^{\circ} n

Divide both sides by

- 1

\frac{- θ}{- 1} = \frac{18 0 ^{\circ}}{- 1} - \frac{3 0 ^{\circ}}{- 1} + \frac{36 0 ^{\circ} n}{- 1}

Simplify

\frac{- θ}{- 1} = \frac{18 0 ^{\circ}}{- 1} - \frac{3 0 ^{\circ}}{- 1} + \frac{36 0 ^{\circ} n}{- 1}

Simplify

\frac{- θ}{- 1} : θ

\frac{- θ}{- 1}

Apply the fraction rule:

\frac{- a}{- b} = \frac{a}{b}

= \frac{θ}{1}

Apply rule

\frac{a}{1} = a

= θ

Simplify

\frac{18 0 ^{\circ}}{- 1} - \frac{3 0 ^{\circ}}{- 1} + \frac{36 0 ^{\circ} n}{- 1} : - \frac{90 0 ^{\circ} + 216 0 ^{\circ} n}{6}

\frac{18 0 ^{\circ}}{- 1} - \frac{3 0 ^{\circ}}{- 1} + \frac{36 0 ^{\circ} n}{- 1}

Apply rule

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

= \frac{18 0 ^{\circ} - 3 0 ^{\circ} + 36 0 ^{\circ} n}{- 1}

Apply the fraction rule:

\frac{a}{- b} = - \frac{a}{b}

= - \frac{18 0 ^{\circ} - 3 0 ^{\circ} + 36 0 ^{\circ} n}{1}

Join

18 0^{\circ} - 3 0^{\circ} + 36 0^{\circ} n : \frac{90 0 ^{\circ} + 216 0 ^{\circ} n}{6}

18 0^{\circ} - 3 0^{\circ} + 36 0^{\circ} n

Convert element to fraction:

18 0^{\circ} = 18 0^{\circ}, 36 0^{\circ} n = \frac{36 0 ^{\circ} n 6}{6}

= 18 0^{\circ} - 3 0^{\circ} + \frac{36 0 ^{\circ} n \cdot 6}{6}

Since the denominators are equal, combine the fractions:

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

= \frac{18 0 ^{\circ} 6 - 18 0 ^{\circ} + 36 0 ^{\circ} n \cdot 6}{6}

18 0^{\circ} 6 - 18 0^{\circ} + 36 0^{\circ} n \cdot 6 = 90 0^{\circ} + 216 0^{\circ} n

18 0^{\circ} 6 - 18 0^{\circ} + 36 0^{\circ} n \cdot 6

Add similar elements:

108 0^{\circ} - 18 0^{\circ} = 90 0^{\circ}

= 90 0^{\circ} + 2 \cdot 108 0^{\circ} n

Multiply the numbers:

2 \cdot 6 = 12

= 90 0^{\circ} + 216 0^{\circ} n

= \frac{90 0 ^{\circ} + 216 0 ^{\circ} n}{6}

= - \frac{\frac{90 0 ^{\circ} + 216 0 ^{\circ} n}{6}}{1}

Apply the fraction rule:

\frac{a}{1} = a

= - \frac{90 0 ^{\circ} + 216 0 ^{\circ} n}{6}

θ = - \frac{90 0 ^{\circ} + 216 0 ^{\circ} n}{6}

θ = - \frac{90 0 ^{\circ} + 216 0 ^{\circ} n}{6}

θ = - \frac{90 0 ^{\circ} + 216 0 ^{\circ} n}{6}

θ = \frac{216 0 ^{\circ} n + 18 0 ^{\circ}}{18}, θ = - \frac{90 0 ^{\circ} + 216 0 ^{\circ} n}{6}

θ = \frac{216 0 ^{\circ} n + 18 0 ^{\circ}}{18}, θ = - \frac{90 0 ^{\circ} + 216 0 ^{\circ} n}{6}

Graph

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Frequently Asked Questions (FAQ)

What is the general solution for sin(θ)=cos(2θ+60) ?
The general solution for sin(θ)=cos(2θ+60) is θ=(2160n+180}{18},θ=-\frac{900+2160n)/6