### Home > PC > Chapter 4 > Lesson 4.1.4 > Problem 4-55

4-55.

In a unit circle, what is the radius?

You have two sides of a right triangle. Find the third side, which is the *x*-coordinate.

In Quadrant III, sine and cosine are both negative.

In which quadrant is sine negative and cosine positive?

In which quadrant is cosine negative and sine positive.