Question
Prove the following:
$\sin ^2 A \cos ^2 B+\cos ^2 A \sin ^2 B+\cos ^2 A \cos ^2 B+\sin ^2 A \sin ^2 B=1$

Answer

$\text { L.H.S. }=\sin ^2 A \cos ^2 B+\cos ^2 A \sin ^2 B+\cos ^2 A \cos ^2 B+\sin ^2 A \sin ^2 B$
$=\sin ^2 A\left(\cos ^2 B+\sin ^2 B\right)+\cos ^2 A\left(\sin ^2 B+\cos ^2 B\right)$
$=\sin ^2 A(1)+\cos ^2 A(1)$
$=1=\text { R.H.S. }$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free