# Trig - Finding Angles

• Jun 25th 2008, 04:01 PM
Nick87
Trig - Finding Angles
Having trouble with my Trig these days. I was wondering if you could help me out?

Q. If Angle B is acute and TanB = $\displaystyle \frac 3{4}$

Find sinB, cosB, sin2B and tan2B

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Also, could anyone help me with another solving for 0 ≤ x ≤ 360 question?

Q. $\displaystyle 4 - sinx = 4cos^2x$

Methods would be great. Thanks! Always appreciative of response (Rofl)
• Jun 25th 2008, 04:14 PM
Quote:

Q. If Angle B is acute and TanB = http://www.mathhelpforum.com/math-he...2ac0d935-1.gif

Find sinB, cosB, sin2B and tan2B
using $\displaystyle \tan = \frac{opposite}{adjacent}$ we can draw a right angle triangle like this:

Attachment 6973

can you continue?

For the last 2 you may like to use these:
$\displaystyle \sin(2x) = 2\sin(x)\cos(x)$
$\displaystyle \cos(2x) = \cos^2(x)-sin^2(x)$
There are other formulas you might know but these are the ones I have memorised.

Quote:

Also, could anyone help me with another solving for 0 ≤ x ≤ 360 question?

Q. http://www.mathhelpforum.com/math-he...5b52d117-1.gif
The first step uses $\displaystyle \sin^2(x)+\cos^2(x)=1$