What is the value of cos(-i) ?

The value of cos(-i) is (e^2+1)/(2e)

English

Español

Português

Français

Deutsch

Italiano

Русский

中文(简体)

한국어

日本語

Tiếng Việt

עברית

العربية

Popular >

cos(-i)

cos (- i)

\frac{e ^{2} + 1}{2 e}

Solution steps

cos (- i)

Use the following property:

cos (- x) = cos (x)

cos (- i) = cos (i)

= cos (i)

Rewrite using trig identities:

cos (0) cosh (1) - i sin (0) sinh (1)

= cos (0) cosh (1) - i sin (0) sinh (1)

Use the following trivial identity:

sin (0) = 0

= cos (0) cosh (1) - i 0 \cdot sinh (1)

Simplify

= cos (0) cosh (1)

Use the following trivial identity:

cos (0) = 1

Rewrite using trig identities:

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

= 1 \cdot \frac{e ^{2} + 1}{2 e}

Simplify

= \frac{e ^{2} + 1}{2 e}

cos (0) - cos (π)

arccos (0.02)

arccos (0.07)

cos (1) π

arctan (\frac{12}{19})