Advertisements
Advertisements
Question
Express the following as the product of sine and cosine.
sin A + sin 2A
Solution
sin A + sin 2A = 2 sin`(("A + 2A")/2) cos (("A - 2A")/2)` ...`[∵ sin "C" + sin "D" = sin (("C + D")/2) cos (("C - D")/2)]`
= 2 sin `"3A"/2` cos `"A"/2` ...[∵ cos(-θ) = cos θ]
APPEARS IN
RELATED QUESTIONS
Prove that:
cos 55° + cos 65° + cos 175° = 0
Prove that:
Prove that:
Prove that:
sin 3A + sin 2A − sin A = 4 sin A cos \[\frac{A}{2}\] \[\frac{3A}{2}\]
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 \[\frac{\sin A + \sin 3A}{\cos A + \cos 3A}\]
If A, B, C are in A.P., then \[\frac{\sin A - \sin C}{\cos C - \cos A}\]=
Express the following as the product of sine and cosine.
cos 2A + cos 4A
Express the following as the product of sine and cosine.
sin 6θ – sin 2θ
Prove that:
cos 20° cos 40° cos 80° = `1/8`
