I’m tinkering with some cardboard modelling, and I need to know how to get the length of an arc. I know how to get the circumference of a circle, but this is eluding me and my rusty O Level Maths (grade C).

So:


I need to know the length of the red line. X and Y are known sizes, and the red line (in this instance) is part of a circle.

However, just to muddy the waters a little, it may be that the red line is a section of an ellipse:


The fact that the shapes are both symmetrical should help.

So, what]s the magic formula? Thanks.

Oooh - handy. Thanks

are you too lazy to read the bible? or did it not specify the blueprints of noah's........


nvm

I knew it...