## Hope99 Group Title Solving trigonometric equations! Help! one year ago one year ago

1. Hope99

How did 3(1-cos^2x)+cos^2x = 2 Became: 3 - 2cos^2x=2 ?! Could you guys help me with this one!

2. Hope99

Why didnt we multiple 3 by (1 - cos^2x) as a whole? Thanks!

3. campbell_st

you need to solve for x so start with $1 - \cos^2(x) = \sin^2(x)$ and substituting will give $3\sin^2(x) + \cos^2(x) = 2$ or $2 \sin^2(x) + \sin^2(x) + \cos^2(x) = 1$ and $\sin^2(x) + \cos^2(x) = 1$ so you have $2 \sin^2(x) + 1 = 2$ or $2\sin^2(x) = 1$ you should be able to solve for x now in my solution I've tried to show every step so you can follow it... there are quicker solutions...