How to Draw Common External Tangent of 2 Circles?

[basty]

Can someone tell me please how to draw common external tangent of 2 circles such as below pic? Please teach me the technical drawing method of it. Thanks

 

 

[eldon]

1. Draw a circle with QP as diameter.
2. Set radius to 2 and draw arc to intersect this circle at T
3. Draw QT and extend to R
4. Draw PT
5. Set radius to PR and centered on T draw an arc at S
6. Draw RS

 

Do you want the theory as well?

 

 

Edited September 10, 2022 by eldon
added to

[basty]

How do you draw like below?

 

 

[eldon]

That is a task for later. I am thinking about it.

 

It is so much easier with AutoCAD!

[eldon]

Assuming this is to be drawn with a compass and ruler (as the previous), here is how I would do it:
1 Draw a circle with AE as the diameter.
2. The crux of the problem is drawing arcs which have a radius of the difference between those of the circles. In the previous example, that was easy because the figure had dimensions. So set the radius as AG. Then centered on H draw the arc at J. Centered on E, put the radius as EJ, and draw the arcs ro give K and L.
3. Draw EK and EL and extend to circumference at D and F
4. Set radius at AD, then centered on K and L, draw arcs at B and C
5. Draw DB and FC

 

 

 

Edited September 11, 2022 by eldon
corrected

[lrm]

@eldon

 

In an earlier post you stated:

1. Draw a circle with QP as diameter.
2. Set radius to 2 and draw arc to intersect this circle at T
3. Draw QT and extend to R
4. Draw PT
5. Set radius to PR and centered on T draw an arc at S
6. Draw RS

 

I think step 5 should be 

5. Set radius to TP and draw arc cenetered at R to determine S.

[eldon]

34 minutes ago, lrm said:

@eldon

 

In an earlier post you stated:

1. Draw a circle with QP as diameter.
2. Set radius to 2 and draw arc to intersect this circle at T
3. Draw QT and extend to R
4. Draw PT
5. Set radius to PR and centered on T draw an arc at S
6. Draw RS

 

I think step 5 should be 

5. Set radius to TP and draw arc cenetered at R to determine S.

 

 

It is heartening to see others who can see the basic geometry - thank you.

 

I was trying to match diagonals of the right angled rectangle, but your solution matches the side length. Both solutions should give the same answer (I hope!)

[lrm]

Yes, you are correct, both methods will work!  I was fixated on the fact that since RT and SP  are parallel, RS = TP but of course, the diagonals of a rectangle will be equal as well.

[SLW210]

I have moved your thread to the AutoCAD 2D Drafting, Object Properties & Interface Forum.