# Physics Trigonometry Problem.

1. Sep 14, 2006

### Arkronus

Hello, I am currently in beginning physics and we are learning a lot about Trig onometry. A homework problem is really bugging me. Here's what it says:

Find the angle A, given the altitude and arc length of the figure shown:
(the picture is in the attachment and also some work i have done.)

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2. Sep 14, 2006

### Arkronus

testing if i can put the image on this post.

3. Sep 15, 2006

### andrevdh

I can also solve it only numerically for the ratio

$$\frac{\sin(A)}{A}=0.719$$

which gives A as 0.8658 radians

Last edited: Sep 15, 2006
4. Sep 15, 2006

### J77

When you say you "believe the hypotenuse is the radius"... it doesn't look it in your sketch.

Last edited: Sep 15, 2006
5. Sep 15, 2006

### HallsofIvy

Staff Emeritus
Basically, then, you have a circular arc, of length 4.17 cm. Dropping a perpendicular gives a length of 3 cm. Yes, the hypotenuse of the right triangle is a radius of the circle. sin A= 3/R and, as long as A is measured in radians, RA= 4.17. Since R= 4.17/A, putting that into the first equation you have sin A= 3A/4.17 just as you say. There is no "algebraic" way of solving such an equation. A numerical solution is the best you can do.