Advertisements
Advertisements
प्रश्न
Express the following as the product of sine and cosine.
cos 2A + cos 4A
Advertisements
उत्तर
cos 2A + cos 4A = 2 cos`(("2A + 4A")/2) cos (("2A - 4A")/2)` ...`[∵ cos "C" + cos "D" = 2 cos (("C + D")/2) cos (("C - D")/2)]`
= 2 cos `((6"A")/2) cos ((6 - 2"A")/2)`
= 2 cos(3A) cos (-A) ...[∵ cos(-θ) = cos θ]
= 2 cos 3A cos A
APPEARS IN
संबंधित प्रश्न
Prove that:
cos 10° cos 30° cos 50° cos 70° = \[\frac{3}{16}\]
Express each of the following as the product of sines and cosines:
sin 12x + sin 4x
Prove that:
sin 105° + cos 105° = cos 45°
Prove that:
cos 80° + cos 40° − cos 20° = 0
Prove that:
Prove that:
If \[m \sin\theta = n \sin\left( \theta + 2\alpha \right)\], prove that \[\tan\left( \theta + \alpha \right) \cot\alpha = \frac{m + n}{m - n}\]
Write the value of \[\sin\frac{\pi}{15}\sin\frac{4\pi}{15}\sin\frac{3\pi}{10}\]
Express the following as the product of sine and cosine.
sin 6θ – sin 2θ
Evaluate:
sin 50° – sin 70° + sin 10°
