Question

Sin 25 cos 5 - cos 80 sin 70 = Sin 15 cos 5

Answer 1

This question is purely an application of

2 sinA cos B

Now

1/2 (sin 30 + sin 20) - 1/2 (sin 150 - sin 10)

1/2 ( sin 20 + sin10)

= 1/2 * 2 sin 15 cos 5 = sin 15 cos 5