# Thread: Circle touching a line and a point

1. ## Circle touching a line and a point

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Hi all

I would like to know how to make something like what I attach below.
Its a circle with radius 112, touching a point on the corner, and the circle must touch some point on the line above precisely.
How to make that?
Best Regards

Rangga

2. NB: sorry for the picture. It's actually a circle, but somewhat it appeared to be an oval.

3. Welcome to the forum. One easy, traditional approach would be to create (temporarily) two circles of that size, with their centers at those two known points. Your two circles will intersect at the center of the desired new circle. You can then create your new circle starting at that center point.
The previous technique is a good one to know and understand. The commandline solution to the same problem can be found in the available commandline options of the CIRCLE command, as shown. What you are looking for is TTR meaning a circle which will be tangent to 2 entities, and of known radius.

4. Ahhh but you don't know the tangent point (other than it is tangent).
Make the circle R112 tangent to the top line somewhere along that line (I would use TTR).
Then move with base point the apparent intersection (or it might be actual intersection depending on where you create the circle), move the basepoint to the intersection of those two lines. So Easy!

5. JD point (1 + a known condition) well taken, I had only glanced at the graphic and noticed the 2 little circles, which I took to represent known points, rather than a point and a condition. I was digging up graphics for TTR as you posted. The coffee is just kicking in here, early on a sunday morning.
I've a sneaking suspicion that you'd be using constraints, and maybe a bit of modern technology.
I am a big fan of the APPARENT INTERSECTION snap, use it a lot.

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I would probably go for drawing a circle radius 112 on the corner point, offset the top line downwards 112, and the Intersection of the circle and offset line is the centre point of the required circle. (No Apparent Intersection needed for me)

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