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

1 Answer
Nghi N. · Anjali G
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.

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