Trig Exam 3

Sum and Diff

100

What is cos(A-B) equal to?

cosAcosB+sinAsinB

200

Find the exact value of sin(15deg)

sqrt{6}-sqrt{2}

------------------

         4

300

Rewrite sin(x-3pi/4) in terms of sinx and cosx.

(-sqrt{2}/2)(sinx+cosx)

Double-Angle

100

How many identities are their for cos(2A)?

3

cos²A-sin²A

2cos²A-1

1-2sin²A

300

Let sinA=12/13 and cosA=5/13. find sin(2A)

120

----

169

400

Rewrite tan^4(x) with only powers of one.

3+cos(4x)-4cos(2x)

----------------------

3+cos(4x)+4cos(2x)

Half-Angle

100

What is sin(A/2)?

+-sqrt{[1-cos(2A)]/2}

200

Find tan(5pi/12)

2+sqrt{3}

400

Given that tanA=8/15 and A is in Q3, find cos(A/2).

-sqrt{17}

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     17

S-t-P and P-t-S

100

What is the difference between Product-to-Sum and Sum-to-Product?

Product-to-Sum: Multiplication of trig functions to addition and subtraction of them.

Sum-to-Product: Addition and subtraction of trig functions to multiplication.

200

Rewrite cos(6t)+cos(4t)

2cos(5t)cost

400

Is the following an identity?

4 sin(3x)cos(4x)=2sin(7x)-2sinx

Yes!

Trig Equations

100

What is tan(x) equal to in terms of sine and cosine?

            sin(x)

tan(x)=--------

           cos(x)

200

Find the exact values of tanx=0 between [0,2pi).

0 and pi

300

Find the exact value of 2sinx=-1 between [0,2pi).

7pi/6 and 11pi/6