सिद्ध कीजिए कि
`sin 25^(@)cos 115^(@)=(1)/(2)(sin 40^(@)-1)`

sin25^(@)cos115^(@)=(1)/(2)(sin40^(@)-1)

Prove tha sin25^(0)cos115^(0)=(1)/(2)(sin40^(@)-1)

sin25^@cos115^@=1/2(sin40^@-1)

sin25^@cos115^@=1/2(sin40^@-1)

sin25^@cos115^@=1/2(sin40^@-1)

Prove tha sin 25^0 cos 115^0 = 1/2 (sin 140^0 -1)

Prove that (i) " sin " 80^(@) "cos " 20^(@) - " cos " 80^(@) " sin " 20^(@) =(sqrt(3))/(2) (ii) " cos " 45^(@) " cos " 15^(@) - " sin " 45^(@) " sin " 15^(@) = (1)/(2) (iii) " cos " 75^(@) " cos " 15^(@) + " sin " 75^(@) " sin " 15^(2)= (1)/(2) (iv) " sin " 40^(@) " cos " 20^(@) " + cos " 40^(@) " sin " 20^(@) =(sqrt(3))/(2) (v) " cos " 130^(@) " cos " 40^(@) l + " sin " 130^(@) " sin " 40^(@) =0

(sin 70^(@) + cos 40^(@))/(cos 70^(@) + sin 40^(@)) =

cos20^(@)cos40^(@)-sin5^(@)sin25^(@)=