How to calculate length of arc? Please Help! First of all, Hi, I'm Brandon! :) 18 Years old currently doing A Levels - Uni End of this year! (Not Homework - Coursework!) So I have this design of a speaker system for my Product Design course in A-Level. There are 3 arcs in my design that I need to know the length of for when my school orders the materials to my specific measurements. Here is a picture with measurements of my design from SolidWorks CAD Software. The arc at the top is 100mm high and the side arcs would be 50mm All measurements in mm. I hope this is enough info for you to help me!