Which of the following number(s) is/are rational? (a)`sin15^0` (b) `cos15^0` (c)`sin15^0cos15^0` (d) `sin15^0cos75^0`

sin15^o +cos15^o is:

The roots of the equation 4x^2-2sqrt(5)x+1=0,a r e (a) sin36^0,sin18^0 (b) sin18^0,cos36^0 (c) sin36^0,cos18^0 (d) cos18^0,cos36^0

Express each of the folloiwng as a product (i) sin 75^(@)-sin 35^(@) (ii) cos 65^(@)+cos 15^(@) (iii) sin 50^(@)+sin 40^(@) (iv) cos 35^(@)-cos 75^(@) .

Prove that (cos10^0+sin10^0)/(cos10^0-sin 10^0)=tan55^0

Prove that sin 75^(@) - sin 15^(@) = cos 105^(@) + cos 15^(@)

If cosx=tany ,coty=tanz ,cotz=tanx , then the value of sinx is (a) 2cos18^0 (b) cos18^0 (c) sin18^0 (d) 2sin18^0

Evaluate sin 15^(@) sec 75^(@)

Prove that sin75^o -sin15^o =cos105^o +cos15^o

4(sin2 4^0+cos6^0)=sqrt(3)+sqrt(15)

Find the value of the following: (sin90^(@)+cos60^(@)+cos45^(@))xx(sin30^(@)+cos0^(@)-cos45^(@))