If sinx=1/6sinx=16, find cos(x-pi/2)cos(xπ2)?

2 Answers
Dec 11, 2016

Given sinx=1/6sinx=16

Now cos(x-pi/2)cos(xπ2)

=>cos(-(pi/2-x))cos((π2x))

as cos(-theta)=costhetacos(θ)=cosθ

=>cos(pi/2-x)=sinx=1/6cos(π2x)=sinx=16

Dec 11, 2016

cos(x-pi/2)=1/6cos(xπ2)=16

Explanation:

As cos(-theta)=costhetacos(θ)=cosθ,

we have cos(x-pi/2)=cos(-(pi/2-x))=cos(pi/2-x)cos(xπ2)=cos((π2x))=cos(π2x)

But, cos(pi/2-x)=sinx=1/6cos(π2x)=sinx=16

Hence, cos(x-pi/2)=1/6cos(xπ2)=16