Question

Find all possible values for θ if 0° < θ < 360° and tanθ = -1.

a. -225°
b. -45°
c. 135°
d. 225°
e. 315°

Answer 1

when tan theta = 1 theta = 45 degrees in the first quadrant.

When its = -1 one value of theta is -45 degrees.

Also as the tangent is negative in the second quadrant theta can also be 135 degrees or - 225 degrees.
in fourth quadrant we have 315 degrees.
Its not 225 degrees because the tangent is positive in 3rd quadrant.

Correct answer is a, b, c and e.