If cos(pi/2-X) =4/5. Find sin(-x)

Question

 Please help me solve this equation to better help me to understand trig Identites.

Answer 1

Pablo

 

cos [(π/2) - x]

find sin (-x)

 

Recall that sin x = cos [(π/2) -x]

and sin(-x) = -sin (x)

 

Sin(-x) = -4/5