Question

Use a sum or difference identity to find the exact value sin 10° cos 110° + cos 10° sin 110°

A. -√3/2
B. √3/2
C. 1/6
D. -1/2

Answer 1

B

Explanation:

using the identity

• sin(x + y) = sinx cosy + cosx siny

given

sin10°cos110° + cos10° sin110°

= sin(10 + 110)°

= sin120°

To obtain related acute angle

= sin(180 - 120)°

= sin60°

=
`(√(3) )/(2)`