# I cant find theta

1. May 27, 2010

### caljuice

http://photoshare.shaw.ca/image/6/8/e/231110/q-0.jpg

I cant find theta. Anyone help me out here?

x=theta

I've tried making Fab=(160cosx)/cos40

Then plugging it in into the second equation, we get

160cosxtan40+160sinx-200=0

160(cosxtan40+sinx)=200

cosxtan40+sinx=1.25

Is there a trig identity here? Far as I can get.

I also tried
cosx=(Fabcos40)/160
sinx=200-(Fabsin40)

Then tanx= [200/(Fabsin40)]-tan40, but no way to eliminate Fab. Or at least I can't.

Last edited: May 28, 2010
2. May 27, 2010

### kuruman

Re: Equilibrium

Maybe it's just me, but I cannot see an image at the link you provided.

3. May 27, 2010

### caljuice

Re: Equilibrium

nope you're right, looks like they took down the image. But fixed!

4. May 27, 2010

### kuruman

Re: Equilibrium

I now see a bunch of equations, but no figure to relate them to.

5. May 27, 2010

### caljuice

Re: Equilibrium

Oh, I'm just wondering how to solve theta from those 2 equations. Didn't think a diagram was needed.

6. May 28, 2010

### kuruman

Re: Equilibrium

If the equations are correct, then this is what you do. Solve each equation for the unknown trig function. You will bet

sinθ = A
cosθ = B
where A and B are numbers you can calculate. Divide the top by the bottom to get

tanθ = A/B. From this get the angle.

7. May 28, 2010

### caljuice

Re: Equilibrium

Sorry, I actually put in a divide sign instead of a minus for sinx, not sure how i missed it.

sinx=200-(Fabsin40)

8. May 28, 2010

### kuruman

Re: Equilibrium

It makes no difference. The method is the same.