SOLUTION: Rewrite the expression as the sine, cosine, or tangent of a double-angle. Then find the exact value of the trigonometric expression without the use of a calculator.

Question 1100862: Rewrite the expression as the sine, cosine, or tangent of a double-angle. Then find the exact value of the trigonometric expression without the use of a calculator.
2cos^2 (-30�)-1
a. Use the appropriate double-angle formula to rewrite the given expression as the sine, cosine, or tangent of the corresponding double-angle.
(Do not evaluate. Type your answer in degrees.)
b.Find the exact value of the trigonometric expression without the use of a calculator.
(Use integers or fractions for any numbers in the expression. Type an exact answer, using radicals as needed.)

Answer by greenestamps(13200) (Show Source): You can put this solution on YOUR website!

(a) is a double angle formula for cosine; so

(b) -60 degrees is a reference angle of 60 degrees in quadrant IV; cosine is the x value on the unit circle; that is the short leg of a 30-60-90 right triangle; its length is 1/2.

Answer:
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SOLUTION: Rewrite the expression as the&#8203; sine, cosine, or tangent of a&#8203; double-angle. Then find the exact value of the trigonometric expression without the use of a calculator.

SOLUTION: Rewrite the expression as the sine, cosine, or tangent of a double-angle. Then find the exact value of the trigonometric expression without the use of a calculator.