1+ ^2 2 A is equal to - Vidyadip

MCQ

$1+\cos ^2 2 A$ is equal to

A
$\sin ^4 A+\cos ^4 A$
B
$\sin ^2 2 A$
✓
$2\left(\cos ^4 A+\sin ^4 A\right)$
D
$2\left(\cos ^4 A-\sin ^4 A\right)$

✓

Answer

Correct option: C.

$2\left(\cos ^4 A+\sin ^4 A\right)$

(C)
$1+\cos ^2 2 A=\left(\cos ^2 A+\sin ^2 A\right)^2$$+\left(\cos ^2 A-\sin ^2 A\right)^2$
$=2\left(\cos ^4 A+\sin ^4 A\right)$

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