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How do I draw an isosceles triangle with a requested/wished angle?

Asked by Per Olesen

First: I have now drawn an isosceles trapezium with the exact measures of the bottomline being 8 cm and the topline being 5 cm and the height 3,5 cm. How do I now measure up the exact degree of the angle that is placed where the bottomline meets the line of the rightside that is leaning towards left seing the trapezium in profile? Can I measure the angle out as I dont know how to calculate the angle if that is possible at all?

Second: Having the degrees of this angle I would like to draw an isosceles triangle with the exact angle I have just measured up. This exact angle I will use where the 2 isosceles lines meet. When I have drawn this isosceles triangle which has the cirka measures as following here: the 2 isosceles lines is about 3,4 cm each and the last line is cirka 2,6 cm. I would now let the left line of this triangle overlap the right line of the trapezium exactly so this left line is centered in the middle of the right line of the trapezium. How do I do that?

When I am finished drawing the result should be an espressocup with a small triangle as handle. This is when you imagine the espressocup in profile. The cup will be produced and will have the shape of a truncated cone being smallest in the top and largest in the bottom. I only want to draw in 2 dimensions as this is what the producer of this espressocup request. Later I guess I would like to draw in 3 dimensions if you can answer me if inkscape can be used for 3 dimensions drawing? For example this espressocup in 3 dimensions later.

If this explanation is not sufficient please do not hesitate to ask me questions. I also have the drawing written in free-hand and I can scan it and send it via email.

Enjoy your espresso and Thanks - Per from Denmark

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Best c (cjue) said : 		#1

Not quite able to visualize your design but here are a couple things that might help you construct it:
1) measuring angles - No dedicated tool presently exists for this but you can use the pen tool to get a reading. To measure the angle of a line from horizontal, first enable the snapping to nodes option. Next, use the pen tool to start a line at one end of the line to be measured. As you move the pen tool around to draw another point, the status bar at the bottom of the screen shows the new line's angle. If you snap the second point to the other end of the line to be measured (without clicking), the angle readout is the angle of interest.
2) You may not need to measure the angle to get your isosceles triangle - Again with the snap to nodes option enabled, draw a line exactly over one of the sides of the trapezium to get a line with exactly the same angle. With this new line still selected, select Object-Flip Horizontal to get a mirrored line that I think will be appropriate for forming the opposite side of your isosceles triangle.
c

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c (cjue) said : 		#2

PS - Inkscape is not a 3D modeler but does have aides for 2 and 3 point perspective drawing.
c

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Per Olesen (perolesen) said : 		#3

Hi ....The problem is now solved...Thanks from Per from Denmark

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Espen Klem (eklem) said : 		#4

Thanks from me to. Used a little time though to find where to look. Look at the status bar when you draw with the pen-tool.