Prove that `15c_2=105`

Prove that 15_(C_(2)=105).

prove that 15_(C_(2)) =105

Prove that (i) "cos " 15^(@) - " sin " 15^(@) = (1)/(sqrt(2)) (ii) " cot " 105^(@) - " tan " 105^(@) =2sqrt(3) (iii) (tan 69^(@) + tan 66^(@))/(1-tan 69^(@) tan 66^(@)) =-1

Prove that: s in105^(@)+cos105^(0)=cos45^(@)

Prove that cos(2 pi)/(15)cos(4 pi)/(15)cos(8 pi)/(15)cos(14 pi)/(15)=(1)/(16)

Prove that cos pi/15 * cos 2pi/15* cos3pi/15 ... . . to 7 factors = 1/2^(7) .

Prove that : (i) "sin"105^(@)+cos105^(@)=(1)/(sqrt(2)) (ii) cos105^(@)+cos15^(@)="sin"75^(@)-"sin"15^(@)

Prove that: sin15^(@)=(sqrt(3)-1)/(2sqrt(2))

Prove that: sin15^(@)=(sqrt(3)-1)/(2sqrt(2))

Prove that :16cos2(pi)/(15)cos4(pi)/(15)cos8(pi)/(15)cos16(pi)/(15)=1