Question

If sin 18° = 0.3090,cos 18° = 0.9511, sin 22° = 0.3746, and

cos 22° = 0.9272, then what is sin 40°?​

Answer 1

0.6428

Explanation:

Using the addition formula for sine

sin(x + y) = sinxcosy + cosxsiny

Hence

sin40 = sin(18 + 22)

= sin18cos22 + cos18sin22

= (0.3090 × 0.9272) + (0.9511 × 0.3746)

= 0.2865 + 0.3563

= 0.6428