Question

find the value of sin20° sin40° sin60° sin80°

Answer 1

lord help you little soul...

Answer 2

sin60= √3/2
=>√3/2(sin20 * sin 40 * sin 80)
=>√ 3/4 [(2sin20sin40)sin80]
on applying [cos(A-B)-cos(A+B) = 2sinAsinB]
we get,
= √ 3/4 (cos20-cos60)sin80 [since,cos(-a)=cosa]
= √ 3/4(cos20sin80-cos60sin80)
= √ 3/8(2sin80cos20-sin80)
= √ 3/8(sin100+sin60-sin80)
= √ 3/8( √ 3/2+sin100-sin80 )
= √ 3/8( √ 3/2+sin(180-80)-sin80 )
= √ 3/8( √ 3/2+sin80-sin80 ) [since,sin(180-a)=sina]
= √ 3/8( √ 3/2)
= 3/16

Hope it helps u....
if yes, mark brainliest...
have a gr8 day ahead...

@TeraBhalaHo