USING ORIGAMI TO CREATE AN EQUILATERAL TRIANGLE FROM A RECTANGLE (A4, A5 OR A6)

Keep in mind that all sides of this triangle will be of equal length and the inside corners will be 60 degree corners.

Light blue equilateral triangle

Instructions

Step 1

Place your rectangle down in portrait orientation - short edges at the top and bottom.

Step 2

Create a vertical center crease line by bringing the left long edge to meet the right long edge. Crease and then unfold.

Step 3

Bring the bottom right corner up to meet the center crease you just created. The fold should start from the lower left corner Make sure not to complete the crease until you obtain a very clear straight line segment stretching all the way from the bottom left corner to the center vertical line. Crease and leave folded.

Step 4

Now, bring the top right corner downwards, towards you as far as it will go, making sure that the right edge of this new fold lines up with the already-folded hinged edge of the previous step. The top of the shape should now form a long horizontal hinge, sloping into a small point at the far left of the shape.

Step 5

Using a mountain crease, fold the just-mentioned small point away from you as far as it will go so it disappears behind the figure. You will now be left with the folded representation of your equilateral triangle.

Step 6

Unfold the last small triangle as well as the left and right sides of the figure to reveal your final triangle.

Step 7

Cut or tear off all three of the pieces you unfolded in the previous step to be left with your usable, single-layered equilateral triangle.

Tip: All corners and sides should match. To check your work, you can fold each side of the triangle in half. If the sides and corners match perfectly, your triangle is ready for use.

[Source: Beginner's Book of Modular Origami Polyhedra: The Platonic Solids by Rona Gurkewitz and Bennett Arnstein - Copyright 2008 by Dover Publications Inc.