We form different geometric figures In Inkscape with two basic tools: Rectangle and Circle can do many things, but can't make something as simple as a triangle. Well, not without some kind of trick. We'll learn hot to make triangles in Inkscape with another powerful tool (Polygon), by drawing, constructing or by cutting and existing figure.
Step 1: Use Polygon Tool
1. Click the Polygon tool.
2. Choose regular polygon type.
3. Select the desired number of corners (three for triangles).
Step 2: Define a Triangle
1. Click somewhere in the drawing area. This will define the center of the triangle.
2. Drag the cursor without releasing the mouse button.
3. When the triangle looks big enough, release the button of the mouse. This will define one of the triangle corners. Other two will be set automatically.
Step 3: Place and Color It
1. Click the node, which looks like a small square. It works like a handle and gives you an opportunity to rotate the triangle until it is positioned as you want.
2. With pulling the handle you can still change the size of the triangle.
3. With ctr-shift-F you can color the object (the inside and the border) with any of numerous colors.
This is the easiest of all methods for making triangles in Inkscape, but it makes only equilateral triangles. If you want any other kind of triangle, some kind of tweaking, as will be presented below, is necessary.
Step 4: Draw a Triangle Wit a Pen
1. Select the so-called Pen or "Draw Bezier Curves" tool (shift-F6).
2. While it's useful as it is, it will be easier to make straight lines with a 'Create a sequence of straight line segments" option.
3. Click where you want the first of the corners to be.
Step 5: Draw Each Line Separately
1. Move the tool to draw a line of a triangle and click the right mouse button for defining the second corner.
2. Move your mouse to the location of next corner. Click again.
3. Move the mouse back to the starting point (first corner). Be careful. The node (small rectangle) should change the color before you make the final click and release. You got a triangle!
Step 6: Manipulate a Triangle According to Your Demands
1. For further tweaking you triangle, press F2 or click the Edit paths by nodes tool. This gives you handles for several kinds of manipulation.
2. Of course you can also click the Select and transform objects (or press F1), what gives you similar options of transformations.
Step 7: Experiment With Possibilities
If you are satisfied with the appearance of the triangle but want to change its position, you can rotate it with ctr-shift-M (select Rotate tab) or press the select tool (F1) and click the object twice. In this case, the handles will change their look and you'll have a chance to rotate the selected object around its axis.
Step 8: Construct a Triangle (or Any Other Kind of Object)
In Inkscape we can also construct a triangle by using simple math operations.
1. Make a rectangle with Rectangle tool.
2. Press Select tool (F1), then click the object twice.
3. Rotate a rectangle for approximately 45 degrees (just click on one of the handles and drag around). 30 degrees or 60 degrees will do fine as well.
4. For easier distinguishing we'll color the object by ctr-shift-F (then select the color of your choice from the wheel).
Step 9: Combine Two Objects
1. Make another rectangle. It should be bigger than the first one.
2. Place it over the first object.
Step 10: 'Subtract' One Shape From the Other
1. Use Select tool. Select both objects by holding shift-key while clicking on both rectangles.
2. Press ctr-(MINUS) (or select Path / Difference in the menu). This kind of construction will always make you a right-angled triangle.
This is not the easiest way, but it definitely opens countless options of constructing objects of innovative shapes.
Step 11: An Alternative Way to Make a Righ Angled Triangle in Inkscape
Here is another way of drawing right-shaped triangles in Inkscape:
1. Draw a rectangle with the Rectangle tool. Just Click the icon for the tool, then click for one of the corners and pull the mouse until the diagonal of the rectangle is defined (don't release the mouse button too fast!). When the rectangle is formed, release the button, what will define the opposite corner and form a rectangle.
2. Press ctr-shift-C (Object to Path) to change the figure into lines.
Step 12: Cut a Rectangle to Form a Triangle!
1. Press F2 (Edit paths by nodes) to change corners into nodes.
2. Select one of the nodes, then press ctr-del to delete a part of the rectangle and the rest three nodes will form a triangle.
3. Feel free to manipulate the size of the sides and the rotation of the triangle as already explained.
Step 13: Play With the Options
The same procedures can be used for all kinds of polygons - regular or irregular. It pays to invest some time with playing with them because they are crucial constructing elements in all kinds of drawings.
I hope you learned how to make triangles in Inkscape!