# How do you determine #sintheta# given #sectheta=-7/5, 180^circ<theta<270^circ#?

##### 1 Answer

Nov 16, 2016

#### Answer:

Please see the explanation.

#### Explanation:

The secant is the reciprocal of the cosine:

This is a variant of

Substitute

We are told that we are in the third quadrant so use the negative value: