Question

Given sin theta=-1.
theta= ?
a. 180 degrees
b. 0 degrees
c. 270 degrees
d. 90 degrees

Answer 1

When is sine -1 on the unit circle? Since since is the y-coordinate, a -1 would be between quadrant 3 and 4 on the y-axis, so at 270 degrees

Answer 2

\[\sin \theta = -1 \implies \sin \theta = -\sin(90) \implies \sin(-90) \implies \sin(2 \pi - 90) = \sin(270)\]

\[\sin \theta = \sin(270)\]

\[\theta = 270\]

Answer 3

Thanks guys