`4 cos^3 15^@ - 3 cos 15^@ =`

cos 15^(@) - cos 75^(@) =

4cos^(3)15^(@)-3cos15^(@)=

4sin75^@-3cos15^@=

(sin 75^(@) - sin 15 ^(@))/( cos 75^(@) + cos 15 ^(@)) = (1)/(sqrt3)

Which one of the following number (s) is/are rational? - 1) sin 15^(@) 2) cos 15^(@) 3) sin 15^(@) cos 15^(@) 4) sin15^(@) cos 75^(@)

(cos 15^(@) + sin 15^(@))/(cos 15^(@) - sin 15^(@)) =

Prove that (i) " 2 cos " 45^(@) " cos " 15^(@)=((sqrt(3)+1))/(2) " "(ii) 2 " sin " 75^(@) " sin " 15^(@)=(1)/(2) (iii) " cos " 15^(@) - " sin " 15 =(1)/(sqrt(2))

Prove that (i) " sin " 75^(@) =((sqrt(6)+sqrt(2)))/(4) (ii) (cos 135^(@) -cos 120^(@))/(cos 135^(@) +cos 120^(@)) =(3 -2sqrt(2)) (iii) " tan " 15^(@) +" cot " 15^(@) =4

The value of (cos 15^(@) - sin 15^(@))/(cos 15^(@) + sin 15^(@) is

sin 15^(@) + cos 105 ^(@) = ............ A) 0 B) 2 sin 15 ^(@) C) cos 15^(@) + sin 15^(@) D) sin 15^(@) - cos 15^(@)