# solve for the radius of an arc.

#### richbrune

Joined Oct 28, 2005
114
I'd like to know the formula for finding the radius of an arc if you know the width of a segment of an arc, and the height of the segment, but you can't measure the whole circle.
I can't figure out how to reduce the pixel size of a bitmap without freezing the computer, otherwise I'd send a diagram.

#### hgmjr

Joined Jan 28, 2005
9,027
richbrune said:
I'd like to know the formula for finding the radius of an arc if you know the width of a segment of an arc, and the height of the segment, but you can't measure the whole circle.
I can't figure out how to reduce the pixel size of a bitmap without freezing the computer, otherwise I'd send a diagram.
Is this what you are looking for?

http://mathworld.wolfram.com/CircularSegment.html

hgmjr

#### Nirvana

Joined Jan 18, 2005
58
Hi there, in order to determine the radius or length of an arc we use the formula. S = r θ, where s is the length of the arc, r is the length of the radius and θ is the angle the radius makes with the arc, in radians , so if you are using degrees then convert it in to radians.
Hope That Helps

Nirvana.