# How do draw a triangle with AutoCAD ?

How do draw a triangle with no included right angle, knowing the lengths of all three sides but knowing no angles.?

### 19 Answers

Ok. the best solution which works in every software is that you draw the first line, then draw a circle whose radius equals to the length of second line at the start of the first line. And repeat drawing the circle with the length of third line at the end of the first line.

The result is the intersection of 2 circles which you have to connect the intersection with the start and end of the first line.

If you know the lenghts you can find the angles, or at least one angle. It is simple trigonometry. From then you can draw the trianlge.

Maybe the question was if you only know the length of the sides.

Start the Polygon tool.

Enter number of sides (3)

Instead of picking a center point press E and enter.

Enter the length of an edge and press enter.

This will only create an equilateral triangle. If you want a different type of triangle, you would need to use some of the parametric constraints and dimensions.

This will allow you to constrain the line ends together and then drive the length of the lines with parametric dimensions.

Try using the parametric relations in Autocad. It's a specific toolbar, maybe you will have to activate it. I don't know since witch release of AC they are there but they sure are included in AutoCad mechanical 2011

At the command line type polygon, 3, pick a centerpoint for the triangle, then choose inscribed "I" if you want to size the triangle using a circle radius from point to point or circumscribed "C" using a circle from flat to flat. Here is the text you can cut and paste to create a 1" radius inscribed triangle at 0,0,0.

(command "polygon" "3" "0,0,0" "I" "1")

by using polygon tool you can draw the triangle. as

click on the "polygon"

enter the number of sides(3)

and pick the center point and draw the triangle.

this will allow you to draw the equilateral triangle.

if you know the exact length just draw a line w/ exact length copy & rotate it to 60 deg then mirror it. you have a perfect triangle w/o going to polygon command.

just press 'l' + 'enter button on keyboard'+ 'click on the screen' + 'move the mouse to the right of the point' + 'press length of the triangle' + 'press enter button on keyboard'

now press 'Esc'+ press 'l'+ 'press enter button on keyboard' + 'click on the 1st point' + 'move the mouse upward of the first point'+ 'enter the height of the triangle' + 'press Esc on keyboard'

now press 'L' + 'press enter button on keyboard' + 'click on the point above the ehight of the triangle' + 'now click on the point right to the triangle' + ' now press Esc'

thats all.......:)

Ehsan's way is the only sensible one; using polygon and parametric to construct it only makes the process longer, by all means use parametric to constrain it afterwards, if the drawing needs it.

write "polygon" in command space bottom in auto cad

select first point

then type "3" ( "3" sided triangle if you want pentagon type "5")

select size do you want by mouse

or enter radius of circle

congraulation you make a tri angle

u can use polar co-ordinate method with line command. u can take length and angle. thn u create triangle.

example :

L ENTER

PICK POINT

@2<0

@2<120

@2<240.

U CREATE ALSO HEXAGON PENTAGON & MORE WITH THIS METHOD.

In Autocad 2013 and 2014,go to Draw toolbar,click polygon,enter number 3 to represent the three sided polygon which is a triangle.Then specify the center of the triangle by clicking any where in the drawing area,press in for inscribe circle and ci for circumscribed circle and press enter.When entered a triangle will shown in your drawing model,Finally just specify the radius of circle by typing the required radius and press enter.Thats it.....I hoped my explanation helps..

Simply from Polygon Command>

Step 1 : Select POLYGON command.

2: Type number of corners and press ENTER. (a Triangle have 3 edges or corners)

3. Define the center point of object.

4. Now press "I" for inscribed circle or press "c" for circuminscribed circle and press enter.

DONE

If we assume that the three sides are different sizes, the only method that will work reliably is the intersecting circle plan mentioned above. If, however, two of the sides are the same size, some of the other options above will work. It is important to read all of a question and understand what is being asked before offering a solution. How often have you engineered an elegant plan only to find that the plan did not satisfy the client's requirements?