Question

Find cosif sin = is in the third quadrant.035OA. -OB.OC. 20OD.Reset Selection-

Answer 1

`A.\text{ }-(4)/(5)`

Step-by-step explanation

We want to find the value of cosθ for:

`\sin\theta=-(3)/(5)`

We are given that θ is in the third quadrant. This implies that it is between 180° and 270°.

First, we have to find the value of θ:

`\begin{gathered} θ=\sin^(-1)(-(3)/(5)) \\ \\ θ=-36.87\degree\text{ or }216.87\degree \end{gathered}`

Since θ is in the third quadrant, it implies that:

`θ=216.87\degree`

Now, find the value of cosθ:

`\cos(216.87)=-0.8=-(4)/(5)`

The answer is option A.