Prove the following:
= cos(π+x)cos(−x)sin(π−x)cos(π2+2)=cot2 x
We have
L.H.S. = cos(π+x)cos(−x)sin(π−x)cos(π2+2)=cot2 x
=-cosx.cosxsinx(−sin x)
⎡⎣∵cos(π+0)=−cos θ,cos(−θ)=cos θsin(π−θ)=sin θ,cos(π2+θ)=−sin θ⎤⎦
= −cos2 x−sin2 x=cot2 x= R.H.S.
[cos(π+x) cos(-x)] divided by / sin(π-x) cos(π/2 + x) = cot^2x