MCQ
$2 \cos x-\cos 3 x-\cos 5 x=$
- ✓$16 \cos ^3 x \sin ^2 x$
- B$16 \sin ^3 x \cos ^2 x$
- C$4 \cos ^3 x \sin ^2 x$
- D$4 \sin ^3 x \cos ^2 x$
✓
Answer
Correct option: A.
$16 \cos ^3 x \sin ^2 x$
(A)
$2 \cos x-\cos 3 x-\cos 5 x$
$=2 \cos x(1-\cos 4 x)$
$=2 \cos x 2 \sin ^2 2 x$
$=4 \cos x \sin ^2 2 x$
$=4 \cos x(2 \sin x \cos x)^2$
$=16 \sin ^2 x \cos ^3 x$
$2 \cos x-\cos 3 x-\cos 5 x$
$=2 \cos x(1-\cos 4 x)$
$=2 \cos x 2 \sin ^2 2 x$
$=4 \cos x \sin ^2 2 x$
$=4 \cos x(2 \sin x \cos x)^2$
$=16 \sin ^2 x \cos ^3 x$
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