# If sin theta=4/5 and theta is in quadrant 2, what is the value of tan theta?

##### 1 Answer

May 8, 2016

#### Explanation:

However, as this is an angle in the 2nd quadrant, the adjacent side is an

This leads to

This agrees with what we know from the CAST rule that Tan values are negative in the second quadrant.

Once you know the lengths of the sides of the triangle, you can write down the value of any of the trig ratio's for the angle

We have

The signs will change depending on what quadrant the triangle is in.