What is the value of {sin(90 - x)cos[π - (x - y)]} + {cos(90 - x)sin[π - (y - x)]}?
A. -cosy
B. -siny
C. cosx
D. tany
Answer: Option A
Solution(By Examveda Team)
sin(90 - x)cos[π - (x - y)] + cos(90 - x)sin[π - (y - x)]⇒ cosx{-cos(x - y)} + sinx.sin(y - x)
⇒ -cosx.cos(x - y) + sinx.sin(y - x)
⇒ -cosx(cosx.cosy + sinx.siny) + sinx(siny.cosx - cosy.sinx)
⇒ -cos2x.cosy - cosx.sinx.siny + sinx.siny.cosx - cosy.sin2x
⇒ -cosy(cos2x + sin2x)
⇒ -cosy
Related Questions on Trigonometry
A. x = -y
B. x > y
C. x = y
D. x < y
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