DOUBLE ANGLE TRIG IDENTITIES WORKSHEET

Problem 1 :

The expression 2sin 30° cos 30° has the same value as

a. sin 15°      b. cos 60°     c. sin 60°        d. cos 15°

Solution

Problem 2 :

The expression csc A sin 2A is equivalent to

a. 2sin A        b. 2        c. 2cos A      d. 2cot A

Solution

Problem 3 :

If sin A = 2/3, find cos 2A.

Solution

Problem 4 :

If sin A = 3/5, find cos 2A.

Solution

Problem 5 :

If θ is in Quadrant II and cos θ = -3/4, find an exact value for sin 2θ.

Solution

Problem 6 :

Express cos 2A+sin2Acos A as a single trigonometric function for all values of A for which the fraction is defined.

Solution

Problem 7 :

2sin x cos x - cos 2x = 2sin2x - 1 + sin 2x

Solution

Problem 8 :

cos2x + tan2x sin2x = sec2x sin2x + cos2x

Solution

Problem 9 :

2sin2xtan x=sin 2x

Solution

Problem 10 :

1 + cos 2x -   tan 4x cos 4x = 2cos2x - sin 4x

Solution

Problem 11 :

tan xsin 2x=sec2x2

Solution

Problem 12 :

Solution

Problem 13 :

Solution

Problem 14 :

Solution

Problem 15 :

Solution

Answer Key

1)  sin 60°, Option C

2)  2 cos A, Option C

3)  1/9

4)  7/25

5)  -3√7/8

6) cos A

7)  proved

8)  proved

9) sin 2x

10)  to 15) proved

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