Question

Prove that sin 25° cos 115°=
1/2(sin 40° -1)
​

Answer 1

Answer:

Sin 25° cos 115°= 1/2(sin 40° -1)

0.422618262 * -0.422618262 = 1/2(0.64278761 - 1)

-0.178606195 = -0.178606195

LHS = RHS

Hence proved.