Advertisements
Advertisements
Question
Express the following as the product of sine and cosine.
cos 2θ – cos θ
Solution
cos 2θ – cos θ
`= - 2 sin ((2theta + theta)/2) sin ((2theta - theta)/2)` ...`[∵ cos "C" - cos "D" = - 2 sin (("C + D")/2) cos (("C - D")/2)]`
= - 2 sin `((3theta)/2) sin ((theta)/2)`
APPEARS IN
RELATED QUESTIONS
Prove that:
sin 20° sin 40° sin 80° = \[\frac{\sqrt{3}}{8}\]
Prove that:
sin 10° sin 50° sin 60° sin 70° = \[\frac{\sqrt{3}}{16}\]
Prove that:
sin 20° sin 40° sin 60° sin 80° = \[\frac{3}{16}\]
Prove that:
sin 50° + sin 10° = cos 20°
Prove that:
sin 105° + cos 105° = cos 45°
Prove that:
cos 80° + cos 40° − cos 20° = 0
Write the value of \[\frac{\sin A + \sin 3A}{\cos A + \cos 3A}\]
If sin x + sin y = \[\sqrt{3}\] (cos y − cos x), then sin 3x + sin 3y =
Express the following as the product of sine and cosine.
sin 6θ – sin 2θ
If sin(y + z – x), sin(z + x – y), sin(x + y – z) are in A.P, then prove that tan x, tan y and tan z are in A.P.
