find sin, cos, and tan

Question

The point (1, −1) is on the terminal side of angle θ, in standard position. What are the values of sine, cosine, and tangent of θ? Make sure to show all work.

Answer 1

The coordinate point forms a 45 degree angle with the origin.  Since the point (1, -1) is in the 4th quadrant, sine and tangent is negative and cosine is positive here.

 

sin(45) = -√(2) / 2

cos(45) = √(2) / 2

tan(45) = -1

 

 

To understand why these trig functions are positive and negative in this quadrant, please review my attached document:

 

https://www.wyzant.com/resources/files/330953/trigonometric_functions_in_a_coordinate_system