What is the value of cos(arctan(1/2)-3pi) ?

The value of cos(arctan(1/2)-3pi) is -(2sqrt(5))/5

English

Español

Português

Français

Deutsch

Italiano

Русский

中文(简体)

한국어

日本語

Tiếng Việt

עברית

العربية

Popular >

cos(arctan(1/2)-3pi)

Solution

cos (arctan (\frac{1}{2}) - 3 π)

Solution

- \frac{2 5}{5}

Decimal Notation

- 0.89442 \dots

Solution steps

cos (arctan (\frac{1}{2}) - 3 π)

Rewrite using trig identities:

cos (arctan (\frac{1}{2})) cos (π) + sin (arctan (\frac{1}{2})) sin (π)

cos (arctan (\frac{1}{2}) - 3 π)

Use the Angle Difference identity:

cos (s - t) = cos (s) cos (t) + sin (s) sin (t)

= cos (arctan (\frac{1}{2})) cos (3 π) + sin (arctan (\frac{1}{2})) sin (3 π)

cos (3 π) = cos (π)

cos (3 π)

Rewrite

3 π

2 π + π

= cos (2 π + π)

Apply the periodicity of

cos

cos (x + 2 π) = cos (x)

cos (2 π + π) = cos (π)

= cos (π)

= cos (arctan (\frac{1}{2})) cos (π) + sin (arctan (\frac{1}{2})) sin (3 π)

sin (3 π) = sin (π)

sin (3 π)

Rewrite

3 π

2 π + π

= sin (2 π + π)

Apply the periodicity of

sin

sin (x + 2 π) = sin (x)

sin (2 π + π) = sin (π)

= sin (π)

= cos (arctan (\frac{1}{2})) cos (π) + sin (arctan (\frac{1}{2})) sin (π)

= cos (arctan (\frac{1}{2})) cos (π) + sin (arctan (\frac{1}{2})) sin (π)

Rewrite using trig identities:

cos (arctan (\frac{1}{2})) = \frac{2 5}{5}

cos (arctan (\frac{1}{2}))

Rewrite using trig identities:

cos (arctan (\frac{1}{2})) = \frac{1 + ( \frac{1}{2} ) ^{2}}{1 + ( \frac{1}{2} ) ^{2}}

Use the following identity:

cos (arctan (x)) = \frac{1 + x ^{2}}{1 + x ^{2}}

= \frac{1 + ( \frac{1}{2} ) ^{2}}{1 + ( \frac{1}{2} ) ^{2}}

= \frac{1 + ( \frac{1}{2} ) ^{2}}{1 + ( \frac{1}{2} ) ^{2}}

Simplify

= \frac{2 5}{5}

Use the following trivial identity:

cos (π) = (- 1)

cos (π)

cos (x)

periodicity table with

2 πn

cycle:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} cos (x) - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2} 0 \frac{1}{2} \frac{2}{2} \frac{3}{2}

= (- 1)

Rewrite using trig identities:

sin (arctan (\frac{1}{2})) = \frac{5}{5}

sin (arctan (\frac{1}{2}))

Rewrite using trig identities:

sin (arctan (\frac{1}{2})) = \frac{( \frac{1}{2} ) 1 + ( \frac{1}{2} ) ^{2}}{1 + ( \frac{1}{2} ) ^{2}}

Use the following identity:

sin (arctan (x)) = \frac{x 1 + x ^{2}}{1 + x ^{2}}

= \frac{( \frac{1}{2} ) 1 + ( \frac{1}{2} ) ^{2}}{1 + ( \frac{1}{2} ) ^{2}}

= \frac{\frac{1}{2} 1 + ( \frac{1}{2} ) ^{2}}{1 + ( \frac{1}{2} ) ^{2}}

Simplify

= \frac{5}{5}

Use the following trivial identity:

sin (π) = 0

sin (π)

sin (x)

periodicity table with

2 πn

cycle:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} sin (x) 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2}

= 0

= \frac{2 5}{5} (- 1) + \frac{5}{5} \cdot 0

Simplify

= - \frac{2 5}{5}

Popular Examples

cos(-0.01)

cos (- 0.01)

tan(pi/4)+cot(pi/4)

tan (\frac{π}{4}) + cot (\frac{π}{4})

12sin(120)

12 sin (12 0^{\circ})

6cos(225)

6 cos (22 5^{\circ})

arcsin(0.79)

arcsin (0.79)

Frequently Asked Questions (FAQ)

What is the value of cos(arctan(1/2)-3pi) ?
The value of cos(arctan(1/2)-3pi) is -(2sqrt(5))/5