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

Prove that 15c_2=105

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

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

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

105^(2)

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

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

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