# Line integral of semicircle

1. Nov 11, 2009

### mefisto666

so I have a semi circle that goes from

$$\frac{5\pi}{4} to \frac{\pi}{4}$$

so the angle between the x axis the radius of the circle is 45 degrees.

I have, letting the radius = a)

$$\frac{1}{a} \int \.dl$$

this is going to have an x and y component, I know the x component is 2a in the direction of x, but what about the y component?

Last edited: Nov 11, 2009
2. Nov 12, 2009

### LumenPlacidum

What function are you integrating over that semi-circle?