Question

Cos pi/5- cos 2pi/5 = 1/2 prove

Answer 1

Step-by-step explanation:

1/2(2cospi/5cos2pi/5)-1/4

2cosAcosB=cos(A+B)+cos(A-B)

cos3pi/2+cospi/5-1/2

cos(pi-2pi/5)+cospi/5=1/2

cospi/5-cos2pi/5=1/2,