# Given sin 40° ≈ 0.64, cos 40° ≈ 0.77, sin 15° ≈ 0.26, and cos 15° ≈ 0.97, which expression could be used to estimate sin 55°?

##### 2 Answers

Jun 9, 2018

#### Explanation:

We know that,

Take,

Jun 9, 2018

#### Explanation:

We know that

#sin(a + b) = sinacosb + sinbcosa#

Therefore

#sin(40˚ + 15˚) = sin40˚cos15˚ + sin15˚cos40˚#

#sin(40˚+ 15˚) = 0.64(0.97) + 0.26(0.77)#

#sin(55˚) = 0.82#

And if we use a calculator to estimate

Hopefully this helps!