Save me, mathletes!

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morkus64

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Nov 7, 2004
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So, working on a floor plan and need to find the radius of the circle that contains a particular arc. The distance around the arc is 1136, and the distance in a straight line from the endpoints is 1104.

Help!

TIA!
 

the DRIZZLE

Platinum Member
Sep 6, 2007
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So, working on a floor plan and need to find the radius of the circle that contains a particular arc. The distance around the arc is 1136, and the distance in a straight line from the endpoints is 1104.

Help!

TIA!

That's not enough information to solve for the radius.
 

morkus64

Diamond Member
Nov 7, 2004
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I'm pretty sure it is... If you draw a straight line at 1104 inches wide, there can only be one arc that connects the points with a given length (1136) (well actually two, but one is just a mirror of the other) (well actually, actually infinite, but only if we are talking about 3 dimensions).
 

SKORPI0

Lifer
Jan 18, 2000
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http://en.wikipedia.org/wiki/Circular_segment

257px-Circularsegment.svg.png
 

morkus64

Diamond Member
Nov 7, 2004
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Ok, so i put in the numbers in autocad, and i'm not getting all the numbers to match up. The radius that gives me the right chord and arc length is 1928.

???
 

alphatarget1

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Dec 9, 2001
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Ok, so i put in the numbers in autocad, and i'm not getting all the numbers to match up. The radius that gives me the right chord and arc length is 1928.

???

Solve the 2 equations and 2 unknowns and you'll get the angle + radius.

s=theta*r
c=r*sqrt(2-2*cos(theta))
 
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