prove that cos20 cos 40 cos 60 cos 80=1/16.

prove that cos 10.cos30.cos50.cos70 = 3/16

prove that tan 50 = 2 tan 10 + tan40

1.(1+cos pi/ 8) (1+cos 3pi / 8) (1+cos 5pi / 8) (cos 7pi / 8)=1/8

Prove that sin3x + sin 2x – sinx = 4 sinx cos x/2 cos3x/2

sin10*sin50*sin70=1/8?

sin 105 degree +cos 105 degree =cos 45 degree

Prove the following: cosA / 1 - sinA = tan (45 + A/2)

Find the maximum and minimum values of sin^4x + cos^2x and hence or otherwise find the maximum value of sin^1000 x + cox^2008 x

PROVE THAT

cos³A + cos³(120+A) + cos³(240+A) = 3/4 cos3A

cos4 pi /8+ cos4 3pi /8+ cos4 5pi /8 +cos4 7pi/ 8=3/2  prove it fast rely plssss

cos4 pi / 8+cos4 3pi /8 + cos4 5pi / 8 +cos4 7pi /8 =3/2

if A+B=45 degree.show that {1+tanA}{1+tanB}=2

 Prove that:

4 cosA cos(60-A) cos(60+A) = cos3A