Question
Prove the following trigonometric identities.
If $\cos\text{A}+\cos^2\text{A}=1,$ prove that $\sin^2\text{A}+\sin^4\text{A}=1.$

Answer

$\cos\text{A}+\cos^2\text{A}=1$
$\cos\text{A}=1-\cos^2\text{A}$
$\cos\text{A}=\sin^2\text{A}$
$\text{L.H.S}=\sin^2\text{A}+\sin^4\text{A}$
$=\sin^2\text{A}+(\sin^2\text{A})^2$
$=\sin^2\text{A}+(\cos\text{A})^2$
$=\sin^2\text{A}+\cos^2\text{A}$
$=1=\text{R.H.S}$
$\therefore\ \text{L.H.S}=\text{R.H.S}$

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