Question

Sarah used her calculator to find sin 125°. She wrote down sin 125° = -.57. How could Sarah recognize that her answer is incorrect?

Answer 1

sin125, on the unit circle, should be positive(not negative), since it should be in quadrant two if the angle 125 degrees is in standard position.

Answer 2

The angle is 125° which lies in second quadrant, where sine and co secant values are positive. Sarah found out sin 125° = -.57, which is negative, which is not possible.

Explanation:

We have four quadrants, let positive x axis represent zero axis.

From 0° to 90° all trigonometric values are positive. Quadrant 1

From 90° to 180° only sine and co secant values are positive. Quadrant 2

From 180° to 270° only tangent and cotangent values are positive. Quadrant 3

From 270° to 360° only cosine and secant values are positive. Quadrant 4

Here the angle is 125° which lies in second quadrant, where sine and co secant values are positive. Sarah found out sin 125° = -.57, which is negative, which is not possible.