Hello all, im a n00b, go easy on me.

1st I hope I have this in the correct forum, please move if not

I am designing a lightbox, so I can take some pretty cool photographs, and I want to design it properly first, general maths is ok, but when it comes to calculating the length of the circumference of circles i am stumped.

See my diagram, my light box is to have a quater circle curve, of 10cm radius. What I need to know, is how long the circumference of that quater circle is.

I can then do the rest of the calculations to determin the back wall and the floor.

Many many thanks.

ILMV aka Ben