In Quadrant 3 of the unit circle, what is the sign of the cosine function?

In Quadrant 3 of the unit circle, what is the sign of the cosine function?

• A. Positive
• B. Negative
• C. Zero
• D. Undefined

Answer: (B)

In Quadrant 3 of the unit circle, both the x-coordinates and y-coordinates of points are negative. The cosine function is represented by the x-coordinate of a point on the unit circle. Since the x-coordinates in Quadrant 3 are negative, the value of the cosine function in this quadrant is also negative. This confirms that the answer is correct. It's important to visualize the unit circle, where Quadrant 3 spans from 180 degrees (or π radians) to 270 degrees (or 3π/2 radians), reinforcing that all the x-coordinates (cosine values) in this section are indeed negative.

In Quadrant 3 of the unit circle, both the x-coordinates and y-coordinates of points are negative. The cosine function is represented by the x-coordinate of a point on the unit circle. Since the x-coordinates in Quadrant 3 are negative, the value of the cosine function in this quadrant is also negative. This confirms that the answer is correct. It's important to visualize the unit circle, where Quadrant 3 spans from 180 degrees (or π radians) to 270 degrees (or 3π/2 radians), reinforcing that all the x-coordinates (cosine values) in this section are indeed negative.