Find the exact value of cos 120°.
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e. -0.5.
cos 120° lies in the second quadrant,
We know that in the second quadrant, only sin and cosec are positive rather and all other trigonometric functions are negative
Thus, cos120° = cos(180° - 60°) = cos(-60°) = -1/2 = -0.5