Pre-cal help!! (See Attachment)

Mathematics

1 answer:

MAVERICK [17]3 years ago

7 0

$2cos(x) + 1 = 0$

$cos(x) = -\frac{1}{2}$

The basic angle for 1/2 is 60°, and cosines are negative in the first and third quadrant.

So, you take 180° - 60° = 120° to get the angle in the first quadrant, and 180° + 60° = 240° to get the angle in the third quadrant.

Since only 120° is an option, the answer is B.

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