Angles Transversed with Centripetal Acceleration

Homework Statement

Okay, so the problem is I need to find the radius of curvature for a proton moving through a uniform magnetic field with initial velocity v for some distance d and exiting at angle θ. I was able to get the correct answer; however, I think the apparent assumption made by the person making this problem is wrong.

Homework Equations

sin θ = opposite/hypotenuse.

The Attempt at a Solution

[PLAIN]http://img715.imageshack.us/img715/4710/diagram2.png [Broken]

This is what I think is wrong.

[PLAIN]http://img194.imageshack.us/img194/6984/diagram1l.png [Broken]

This is why I think it is wrong.

If my diagrams need to be further explicated, don't hesitate asking.

Last edited by a moderator: