1) cos 160 degree + sin 70 degree = 0
2) cos 25 degree .tan 65 degree .cot 115 degree .sec 155 degree = 1
3) sin (A + B) + cos (A - B) = (sin A + cos B) (sin B + cos B )
1) cos 160 degree + sin 70 degree = 0
2) cos 25 degree .tan 65 degree .cot 115 degree .sec 155 degree = 1
3) sin (A + B) + cos (A - B) = (sin A + cos B) (sin B + cos B )