# Need help before final

• May 5th 2009, 05:55 PM
coasterguy
Need help before final
I'm trying to figure out how to do these, but I'm lost:

Quote:

Suppose A is in Quadrant IV and tan A = B. Write each one of the following values in terms of B.

cotA=
secA=
cosA=
sinA=
cot(90°-A)=
sin(2A)=

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Quote:

Find all solutions Θ, 0° <= Θ < 360°
cos(3Θ + 15°) = 1/2

Thanks!
• May 5th 2009, 06:06 PM
Shyam
Quote:

Originally Posted by coasterguy
I'm trying to figure out how to do these, but I'm lost:

Thanks!

$\displaystyle \cot A = \frac{1} {{\tan A}} = \frac{1} {B} \hfill \\$

$\displaystyle \sec A = \sqrt {1 + \tan ^2 A} \hfill \\$

$\displaystyle \cos A = \frac{1} {{\sec A}} \hfill \\$

Finish it all.
• May 5th 2009, 06:11 PM
Shyam
Quote:

Originally Posted by coasterguy

cos(3Θ + 15°) = 1/2

Thanks!

$\displaystyle \cos \left( {3\theta + 15^\circ } \right) = \frac{1} {2} \hfill \\$

$\displaystyle 3\theta + 15^\circ = 60^\circ \hfill \\$

finish it.

$\displaystyle {\text{OR}} \hfill \\$

$\displaystyle 3\theta + 15^\circ = 300^\circ \hfill \\$

finish it.