Finding radius of circle inscribed in a triangle

[Bohrok]

Homework Statement

Someone gave me this problem: finding the radius of the circle inscribed in the triangle with the given lengths.

The Attempt at a Solution

The person asking about this problem said it was taken from a beginning algebra textbook. I tried figuring it out using just basic algebra, but I couldn't make any progress. Is this problem solvable with basic algebra/geometry? Would it be any easier if it were a right triangle?

 

[rock.freak667]

What I can deduce that you must use are some of the circle theorems, such as the angle made by a tangent and radius at the point of contact is 90°, as well as possibly some trigonometry.

I believe that the two tangents that meet (made by the 4 unit and 3 unit line) are both equal by one of the circle theorems.