Math CentralQuandaries & Queries


Question from Dale:

I need a formula to figure the lineal footage of trim require to trim an arched or round top window. The variables that I have consist of the width of the window the height of the arc and the radius.


I you use my earlier response to your question of the central angle then you can use the fact that

arc length = radius × (central angle)

as long as you measure the central angle in radians. Thus when you use your calculator to find

central angle = 2 sin-1[c/(2r)]

make sure your calculator is set to return the angle in radians.


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