# Thread: How solve a trigometric function

1. ## How solve a trigometric function

Hey everybody.

I have the following trig function and I have to simplify it so that it will only have sintheta in it. Can you show me how to do that?:

9.78049(1+0.005288sinsquaredx - 0.000006sinsquared2x) (m/ssquared)

I tried pulling out a sinx, but that only seemed to complicate the problem because once I did that had to simplify the sin2x and I just couldn't find a way to do it!

Is there another way to approach this problem? I've exhausted all sources and my book has the most basic concepts possible!

Any help is appreciated,
Stealth

2. Originally Posted by Stealth
Hey everybody.

I have the following trig function and I have to simplify it so that it will only have sintheta in it. Can you show me how to do that?:

9.78049(1+0.005288sinsquaredx - 0.000006sinsquared2x) (m/ssquared)
theta?

$\displaystyle a[1 + b\sin^2{x} - c\sin^2(2x)]$

$\displaystyle a[1 + b\sin^2{x} - 4c\sin^2{x}\cos^2{x}]$

$\displaystyle a[1 + b\sin^2{x} - 4c\sin^2{x}(1 - \sin^2{x})]$

$\displaystyle a[1 + b\sin^2{x} - 4c\sin^2{x} + 4c\sin^4{x}]$

$\displaystyle a[1 + (b-4c)\sin^2{x} + 4c\sin^4{x}]$

3. Originally Posted by skeeter
theta?

$\displaystyle a[1 + b\sin^2{x} - c\sin^2(2x)]$

$\displaystyle a[1 + b\sin^2{x} - 4c\sin^2{x}\cos^2{x}]$

$\displaystyle a[1 + b\sin^2{x} - 4c\sin^2{x}(1 - \sin^2{x})]$

$\displaystyle a[1 + b\sin^2{x} - 4c\sin^2{x} + 4c\sin^4{x}]$

$\displaystyle a[1 + (b-4c)\sin^2{x} + 4c\sin^4{x}]$
Sorry yes it's x not theta. I replaced it with x to make it easier on my eyes. Um....so I can't simplify it anymore right? I can't drop it down to sinx only?

4. Originally Posted by Stealth
Sorry yes it's x not theta. I replaced it with x to make it easier on my eyes. Um....so I can't simplify it anymore right? I can't drop it down to sinx only?
no

5. Ok so I'm not the only one that can't solve it anymore...
Thanks!

Stealth