Question

If sin 20 degree=a and cos20 degree=b then which of the following represents the correct value of sin 70 degree in terms of a and/or b?

1) a+b
2) a
3) b
4)a-b

Answer 1

3) b

Step-by-step explanation

Given that:

`\sin(20 \degree) = a`

and

`\cos(20 \degree) = b`

Recall that the sine and cosine functions are equal for complementary angles.

This implies that,

`\sin(70 \degree) = \cos(20 \degree)`

`\sin(70 \degree) = b`