Question

if theta = 30° Verify the following :- (A) cos 3 theta° = 4 cos cube theta - 3 cos theta (B) sin 3 theta = 3 sin theta - 4 sin cube theta

Answer 1

Hey,
theta =30° (given)
(a)L.H.S.=cos 3*30°=cos 90°=0 (cos 90°=0)
R.H.S.=4 cos ^3 30°-3 cos 30°
=cos 30°(4 cos^2 30°-3) (cos 30°=√3/2)
=√3/2(4*3/4 -3) (cos^2 30°=3/4)
=√3/2(3-3)
=√3/2*0

L.H.S.=R.H.S.
Hence proved
(b)
R.H.S=3 sin 30°- 4 sin^3 30° ( sin 30° =1/2)
=3*1/2 - 4 (1/2)^3
=3/2-4*1/8
=3/2-1/2
=1

R.H.S.=sin 3*30°=sin 90°=1

#hope it helps....

Answer 2

Answer:

Step-by-step explanation: hello sorry I don't know