Circle: Radius + Tangent + Point

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RungeZipperer
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Posts: 5
Joined: Wed Nov 05, 2014 10:11 am

Circle: Radius + Tangent + Point

Post by RungeZipperer » Mon Dec 08, 2014 10:56 am

Hello,

I´m wondering if the combination for drawing a circle out of radius + tangent + point is missing.
slot.png
slot.png (18.37 KiB) Viewed 5600 times
See the example (that´s the goal). How do I draw the 2.23 mm radius? I know the radius, one point (at the slot opening) and I know it´s a tangent to the line that goes up.

So far my drawing looks like this:
qcad.png
qcad.png (4.03 KiB) Viewed 5600 times
I tried all different circle option but I did not find a solution. I guess this problem is quite easy but I just don´t get it.

Can you help me?

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andrew
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Re: Circle: Radius + Tangent + Point

Post by andrew » Mon Dec 08, 2014 11:11 am

A circle with radius R that is tangential to a line has its center R units away from that line:
-> Create a parallel with distance R (2.23) from the line. The center of the solution must be on that parallel.

A circle with radius R that goes through point P, has its center R units away from that point P:
-> Create a circe with center in P, radius R (2.23). The center of the solution must be on that circle.

The intersection between the parallel and the circle you've constructed is the center of your solution:
Screen Shot 2014-12-08 at 11.08.21.png
Screen Shot 2014-12-08 at 11.08.21.png (15.09 KiB) Viewed 5594 times

RungeZipperer
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Posts: 5
Joined: Wed Nov 05, 2014 10:11 am

Re: Circle: Radius + Tangent + Point

Post by RungeZipperer » Mon Dec 08, 2014 11:21 am

Thanks a lot.

Guess I wouldn´t have found this solution without you.

Do you think that this is worth a "feature request" to have one more circle option?

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andrew
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Joined: Fri Mar 30, 2007 6:07 am

Re: Circle: Radius + Tangent + Point

Post by andrew » Mon Dec 08, 2014 11:32 am

Yes, why not. This is really the one combination that is not covered currently (tangent, point, radius).

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