Question

sin 20.
Sin 40
Sin 6o. Sin 80
plove that.
3/16​

Answer 1

Answer:

sin20.sin40.sin60.sin80 let multiple and divide by 4

1/2(sin80°.sin40°)sin20°

1/2*1/2*(2sin80°.sin40°)sin20°

1/4(cos(80+40)-cos(80-40))sin20°

1/4(cos120°-cos40°))sin20°

1/4(cos(180-60)-cos40°))sin20°

1/4(-1/2-cos40°))sin20°

1/8(-sin20-2cos40.sin20)

1/8(-sin20-(sin(60)-sin20)

1/8(-sin20-√3/2+sin20)

=√3/16

check your question it must be √3/16 to proof not 3/16