Determine the quadrant of the angle’s terminal line lies Sin x = -0.45 & cos x < 0 ?

1 Answer
Jun 6, 2018

The angle lies in quadrant 3 .

Explanation:

sin x = - 0.45

Because sinx is negative, angle (arc) x lies either in Q3 or Q4.

Because cos x < 0, x lies in Q. 3.

Note:
Calculator gives 2 values of x:
x = - 26.74^@ and
x = 180 - (-26.74) = 180 + 26.74 = 206.74^@
x = 206.74^@ is the answer.

x lies in Quadrant 3, and
cos (206.74) is negative.