# Shouldn't the answer to this problem be A, not D. Since we are working with the second quadrant, would it be negative... or did I just do it completely wrong? Thank you so much for your help!

##### 1 Answer

Jun 23, 2018

#### Explanation:

Use trig identity

In this case:

Since t lies in Quadrant 2, so, (t/2) lies in Quadrant 1, therefor, cos (t/2) is positive.