Prove that `sin((theta)/(2))sin((7 theta)/(2))+sin((3 theta)/(2))sin((11 theta)/(2))=sin2 theta sin5 theta`

Prove that sin (theta)/(2) sin"" (7 theta)/(2) + sin ""(3theta)/(2) sin ""(11 theta)/(2) = sin 2theta sin5 theta .

sin ((theta) / (2)) sin ((7 theta) / (2)) + sin ((3 theta) / (2)) sin ((11 theta) / (2)) = sin (2 theta) sin (5 theta)

sin""(theta )/(2)* sin""(7 theta )/(2) + sin""(3theta )/(2) * sin""(11 theta )/(2) - sin 2 theta sin 5 theta =

If theta=(pi)/(21), then (sin23 theta-sin7 theta)/(sin2 theta+sin14 theta)=

If theta=(pi)/(21), then (sin23 theta-sin7 theta)/(sin2 theta+sin14 theta)=

Let f_(n)(theta)= 2 sin . (theta)/(2) sin. (3theta)/(2) + 2 sin.(theta)/(2) sin. (5theta)/(2) + 2sin. (theta)/(2) sin. (7 theta)/(2) + ... + 2 sin (2 n+1) (theta)/(2), n in N , then which of the following is/are correct ?

Let f_(n)(theta)= 2 sin . (theta)/(2) sin. (3theta)/(2) + 2 sin.(theta)/(2) sin. (5theta)/(2) + 2sin. (theta)/(2) sin. (7 theta)/(2) + ... + 2 sin (2 n+1) (theta)/(2), n in N , then which of the following is/are correct ?

Let f_(n)(theta)= 2 sin . (theta)/(2) sin. (3theta)/(2) + 2 sin.(theta)/(2) sin. (5theta)/(2) + 2sin. (theta)/(2) sin. (7 theta)/(2) + ... + 2 sin (2 n+1) (theta)/(2), n in N , then which of the following is/are correct ?

Prove that sin theta+sin2 theta+sin4 theta+sin5 theta=4cos((theta)/(2))cos((3 theta)/(2))sin3 theta

Prove that: 4sin theta sin(theta+(pi)/(3))sin(theta+(2 pi)/(3))=sin3 theta