# Thermal expansion/radius of curvature help!

1. Jan 24, 2010

### farmerburns

1. The problem statement, all variables and given/known data

A metal bar is 1.90 m long with a coefficient of thermal expansion of, 1.34e10-5 (K-1). It is rigidly held between two fixed beams. When the temperature rises, the metal bar takes on the shape of the arc of a circle. What is the radius of curvature of the circle when the temperature rises by 50°C? [Hint: You can use the small-angle approximation sin θ = θ -(θ3/6).]

2. Relevant equations
listed in problem

3. The attempt at a solution
I have tried similar triangles, pythagorian theorem, and trig functions. I cannot see how I should use this "small angle approximation". Can someone please point me in the right direction?

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