Verify the identity.

cos(x+pi/2) = -sinx

see explanation

Step-by-step explanation:

Using the cosine addition identity

cos(x + y) = cosxcosy - sinxsiny

and cos() = 0, sin() = 1

cos(x + )

= cosxcos() - sinxsin()

= cosx × 0 - sinx × 1

= 0 - sinx

= - sinx

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