SOLUTION: verify the identity. cos (x + pi/2) =

SOLUTION: verify the identity. cos (x + pi/2) = - sin x

Question 1089214: verify the identity.
cos (x + pi/2) = - sin x
Found 2 solutions by Theo, MathLover1:
Answer by Theo(13342) (Show Source): You can put this solution on YOUR website!
this uses the basic trigonometric identity of:

cos(a + b) = cos(a) * cos(b) - sin(a) * sin(b).

replace a with x and b with pi/2 and you get:

cos(x + pi/2) = cos(x) * cos(pi/2) - sin(x) * sin(pi/2)

cos(pi/2) = 0

sin(pi/2) = 1

you can use your calculator to confirm.

equation bec0omes:

cos(x + pi/2) = cos(x) * 0 - sin(x) * 1

simplify to get:

cos(x + pi/2) = -sin(x)

QED (that's your solution).

Answer by MathLover1(20850) (Show Source): You can put this solution on YOUR website!
verify the identity.

use Sum-Difference Formulas:
cos( � ) = �
in your case,
...........since and

RELATED QUESTIONS
verify the identity cos (x + pi/2) = -sin... (answered by tommyt3rd)
Verify the identity. cos( x (pi/2)) = -sin x (answered by Alan3354)
Use the Angle sum identity to verify: sin(x+(pi/2))=cos... (answered by ikleyn)
Use the Angle sum identity to verify: Question #1. sin(x+(pi/2))=cos... (answered by ikleyn)
how do i verify the identity of sin(x+pi/2)=cos x (answered by Alan3354,Edwin McCravy,ikleyn)
Verify the identity: (cos x-sin... (answered by robertb)
Verify following is an identity. sin((x)+(pi/3))-cos((x)+(pi/6))=sin(x) (answered by Tatiana_Stebko)
Verify the identity. cos (x - y) - cos (x + y) = 2 sin x sin y (answered by solver91311)
Verify the identity. cos (x - y) - cos (x + y) = 2 sin x sin y (answered by lynnlo)