Question

Question #45f6e

Answer 1

When `x = pi/4`

Explanation:

Property of complement arc:
`sin x = cos (pi/2 - x)`
It is possible that sin x= cos x when `cos (pi/2 - x) = cos x`.
Unit circle gives:
`cos (pi/2 - x) = cos x` --> `(pi/2 - x) = +- x`
It happens when
`pi/2 = 2x` --> `x = pi/4`
Check.
When `x = pi/4` --> Trig Table --> `sin x = sqrt2/2` --> `cos x = sqrt2/2`,
then, sin x = cos x.