Faq/Draw/105

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How do I draw a regular equilateral triangle?

The Drawing toolbar has a button to draw an isosceles triangle but not an equilateral triangle. To draw one, you must do a little geometry. In fact, an equilateral triangle is an isosceles triangle whose height h is:

[math]\displaystyle{ h=\mathit{a.}\sin \left(\frac{\Pi }{3}\right)=\mathit{a.}\sin \left(60\circ \right)=\mathit{a.}\frac{\sqrt{3}}{2}\approx a\times \mathrm{0.866} }[/math] with a representing the length of any edge of the triangle.

To draw an equilateral triangle:

click on the triangle to the right of the Basic Shapes icon to open the Basic Shapes toolbar. In the toolbar, click on the Isosceles Triangle button.

click and drag to draw a triangle of about the size desired;
select the Format ▸ Position and sizemenu;
make sure Keep ratio is unchecked;
adjust:
- the height so that it equals the width multiplied by 0.866,
- the width so that it equals the height divided by 0.866,or
- both, maintaining the proportion 0.866 between the height and the width;
If you change the size of the triangle, click Keep ratio to keep the length of the three sides equal.
Click OK.

Another way to create equilateral triangle is to:

Draw first edge:
- Draw a line, holding ⇧ Shift, so it is a straight line.
- Click on it, press F4 to open properties.
- Tab Position and Size, set Width to expected length.
- Click OK.

Draw second edge:
- Copy and paste Ctrl + C, Ctrl + V to create a copy.
- Press F4 to open properties.
- Tab Rotation, select Pivot Point on a left position and set Rotation Angle to 60".
Draw third edge:
- Create another copy of the base line with Ctrl + V.
- Press F4 to open properties.
- Tab Rotation, select Pivot Point on a right position and set Rotation Angle to 300".
Combine edges in one shape:
- Select all lines.
- Select menu entry Shape ▸ Combine or ⇧ Shift + Ctrl + K.