" 7) "cos(pi)/(5)-cos(2 pi)/(5)=(1)/(2)

prove that cos[(pi)/(5)]-cos[(2 pi)/(5)]=(1)/(2)

Prove that: (cos pi)/(5)(cos(2 pi))/(5)(cos(4 pi))/(5)(cos(8 pi))/(5)=(-1)/(6)

cos(pi)/(11)+cos(3 pi)/(11)+cos(5 pi)/(11)+cos(7 pi)/(11)+cos(9 pi)/(11)=(1)/(2)

The value of cos(pi)/(5)cos.2(pi)/(5)cos4(pi)/(5)cos8(pi)/(5)=

Prove that, cos(pi/5)-cos((2pi)/5)=1/2

cos((pi)/(15))cos((2 pi)/(15))cos((pi)/(5))cos((4 pi)/(15))cos((2 pi)/(5))cos((7 pi)/(15)) is equal to

The most general value of x satisfying the equation tan x=(1+sin backslash(pi)/(5)-cos(2 pi)/(5))/(cos backslash(pi)/(5)+sin backslash(2 pi)/(5)) is

Prove that: cos(pi/5)cos((2pi)/5)cos((4pi)/5)cos((8pi)/5)=(-1)/16

The value of cos[(1)/(2)cos^(-1)cos((14 pi)/(5))]is(a)cos((2 pi)/(5))(b)cos(-(7 pi)/(5))(c)sin((pi)/(10))(d)-cos((3 pi)/(5))

The value of cos[(1)/(2)cos^(-1)(cos(-(14 pi)/(5)))] is/are a.cos (-(7 pi)/(5)) b.sin((pi)/(10))ccos((2 pi)/(5))d.-cos((3 pi)/(5))