Question

Using the unit circle, determine the value of cos(-150°).

Answer 1

Answer:
`-(√(3))/(2)`

Step-by-step explanation:

The identity we'll use is cos(-x) = cos(x) for any value of x.

So cos(-150) = cos(150).

Then locate the angle 150 on the unit circle. The terminal point is
`\left(-(√(3))/(2), (1)/(2)\right)`

The x coordinate of this terminal point is the value of cos(150).

Answer 2

Cos(-150°)=-√3/2

Step-by-step explanation:

-150° is found at the third quadrant so the cost value at third quadrant is negative

Cos(-150°)= -cos(30)=-cos(210)

Cos(-150°)=- (√3/2)

Cos(-150°)=-√3/2

Hope it helps