Problem on drawing an inscribed rectangle

[stevejai]

Hi all,

 

I am learning autocad by myself, right now I am stucked on a self-learning exercise.

 

I have no idea how to draw an inscribed rectangle like this, which its length is 2 times its width. just hope someone can teach me

[ReMark]

My non-mathematical approach.

 

 

I like this one better. I used the Circle, Line, Extend, Mirror and Rectangle commands. I also included the finished version.

[JD Mather]

Since you are using 2014 you can find a Parametric solution.

Create the circle and add parametric diameter dimension.

(become familiar with Nearest osnap which will give you Coincident constraints)

Draw horizontal line.

Draw half vertical line (don't worry about getting it exact size).

Draw second half vertical line.

Make the vertical lines Equal (=) constraint equal to the horizontal line.

 

You can now test by editing the circle diameter.

 

X=33.541019662

Edited September 25, 2013 by JD Mather

[paulmcz]

another way

[Dana W]

My non-mathematical approach.

 

[ATTACH]44149[/ATTACH]

 

I like this one better. I used the Circle, Line, Extend, Mirror and Rectangle commands. I also included the finished version.

This doesn't appear to achieve the desired result of a rectangle with a width of 1x and a length of 2x. I would like to know how to establish that myself, if there is a way without using math. Math is so cumbersome, all full of numbers and stuff, and my current version of CAD has no constraints.

 

I suppose one could just draw a rectangle of the correct proportions, cross it with a diagonal line, then scale the rectangle so the line = 075 units, then move it to the proper position in the circle.

[steven-g]

Apparently a picture is worth a thousand words, but needs at least 10

[stevejai]

Thanks for all I tried the paulmcz's method, it really works, the length is 2 times to the width. thank you so much.

 

To: Dana W, I tried your method too, I tried to make a rectangle, cross it with a diagonal line, then put it in the circle and scale it, but its length isn't 2 times to its width, and the rectangle does not touch the circle, err am I missing somethings?

 

 

err...its not easy to self-learning cad, i feel so noob

Edited September 26, 2013 by stevejai

[Dadgad]

While I admire the logic in paulmcz's solution,

it looks to me like steven-g's solution is a lot easier and quicker.

 

Might want to use 4 identical triangles though.

You could make it large enough to cover any likely circles,

put it on a toolpallete, and then it would always be ready to

drop onto the center of any circle, yielding you 4 corner points of intersection

with whatever circle you chose.

[eldon]

Even another way.

 

First of all draw the circle.

 

Then from the centre point, draw a horizontal line 1 unit (or multiple), then a vertical line 2 units and then close the triangle. Extend this diagonal line until it reaches the circle at both ends. Use the Rectangle command with the pick points at each end of the diagonal line.

[Dadgad]

Poetry in motion.

[PotGuy]

I assume then that Perpendicular wouldn't yield the solution you were after?

 

Also, love that solution Eldon.

[stevejai]

oh cool, eldon's method works too.

 

anyone know how to make the corner of the rectangle perfectly line on the circle? as I zoom in, there are no intersection point between the circle and rectangle, [i uploaded a "zoom in" in previous post]

[Dadgad]

oh cool, eldon's method works too.

 

anyone know how to make the corner of the rectangle perfectly line on the circle? as I zoom in, there are no intersection point between the circle and rectangle, [i uploaded a "zoom in" in previous post]

 

If you hit RE you may find that when regenerated they do intersect.

If not you can scale up the line from the center of the circle by a random amount

to ensure that they do intersect. Then use the Rectangle command starting

from one Intersection Osnap point to the other, case closed, done deal.

[Dana W]

Thanks for all I tried the paulmcz's method, it really works, the length is 2 times to the width. thank you so much.

 

To: Dana W, I tried your method too, I tried to make a rectangle, cross it with a diagonal line, then put it in the circle and scale it, but its length isn't 2 times to its width, and the rectangle does not touch the circle, err am I missing somethings?

 

[ATTACH=CONFIG]44165[/ATTACH]

 

err...its not easy to self-learning cad, i feel so noob

I have only been CADing since 2006, and I feel like a noob too. Besides, I never took any advanced math classes beyond plane geometry.

 

You need to draw the rectangle at the 1:2 relationship before scaling, and then make sure the aspect (x,y) ratio stays while scaling. Still, accuracy depends on how well one can handle scaling to a reference. Mine is not the best solution.

[stevejai]

Thanks for all you guys helping.

 

Thank you so much.