Show that : `cos 70^0.cos10^0 + sin 70^0 . Sin10^0 = 1/2`

(2cos 40^0-cos 20^0)/(sin 20^0)=

Show that sin70^(0)cos10^(0)-cos70^(0)sin10^(0)=(sqrt(3))/(2)

cos25^(0)cos35^(0)-sin10^(0)sin20^(0) ,

If cos(x - y)= -1 , show that cos x + cos y = 0 and sin x + sin y = 0 .

Prove that (i) sin 70^(@) cos 10^(@) -cos 70^(@) sin 10^(@) =(sqrt(3))/(2) (ii) cos 50^(@) cos 10^(@) -sin 50^(@) sin 10^(@) =(1)/(2) (ii) cos 80^(@) cos 20^(@) + sin 80^(@) sin 20^(@) =(1)/(2) (iv) sin 36^(@) cos 9^(@) + cos 36^(@) sin 9^(@) =(1)/(sqrt(3))

Show that:- cos130^(@) cos40^(@)+"sin"130^(@)"sin"40^(@)=0 .

cos70*cos10+sin70*sin10=(1)/(2)

Show that det[[sin10^(0),-cos10^(0)sin80^(@),cos80^(@)]]=1

sin50 ^ (@) - sin70 ^ (@) + sin10 ^ (@) = 0

The value of the expression (1-4sin 10^0 sin 70^0)/(2sin 10^0 ) is- a.1/2 b. 1 c.2 d. none of these