Calculating Percentage Error for a Circular Disc with (10 +/- 0.2)cm Radius

[Boogeyman]

Homework Statement

A circular disc has a radius of (10 +/- 0.2)cm. Determine the percentage error in the determination of its circumference.

The Attempt at a Solution

I know that percentage error is found by absolute error divided by measurement x 100. The absolute error here is 0.2cm, and the measurement is 10cm. But what do I have to do with circumference?

 

[Kalvarin]

Have you used the error equation before?

If we want to work out the absolute error on C and C = 3A, then,

(error on C)^2 = ((dC/dA)*(error on A))^2

From memory i think it's that. So imagine the circumference is C and make an equation for it. You should be able to get it from that.