Pentagram Triangles

How many triangles are formed?

Magic Triangle

Place the digits 1 through 9 in the circles in a very special way.

Counting Triangles

Determine the number of triangles in the diagram.

Non-Overlapping Triangles

Use three lines to form as many triangles as possible.

Lining Up to Find Triangles

Draw lines to find the largest amount of triangles.

Toothpick Transfer

Readjust a diagram to form a number of triangles.

Hidden Triangles

Count the number of triangles in a picture.


Explore Symmetry with Altitudes and Medians.

Triangular Numbers

Explore the sequence of triangular numbers.

Triangles Inscribed Inside Triangles

Explore properties of triangles constructed using the midpoint of given triangles.