Question

evaluate cos930degree​

Answer 1

Step-by-step explanation:

Remove full rotations of

360° until the angle is between

0° and 360°

cos (210)

Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because cosine is negative in the third quadrant.

-cos(30)

The exact value of

cos(30) is

√3/2 -√3/2

The result can be shown in multiple forms.

Exact Form:

-√3/2

Decimal Form:

0.86602540.

Answer 2

Answer:

Step-by-step explanation:

Remove full rotations of

360° until the angle is between

0° and 360°

cos (210)

Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because cosine is negative in the third quadrant.

-cos(30)

The exact value of

cos(30) is

√3/2 -√3/2

The result can be shown in multiple forms.

Exact Form:

-√3/2

Decimal Form:

0.86602540.