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How many triangles do you see?

How many triangles do you see?

How many triangles can you find in this pentagon?

Solution

Since the figure is drawn on a regular pentagon and if we turn it the fifth part of a turn it becomes itself, each triangle we find will be repeated five times, so that we can save some of the work. So we can find 7 different types of triangles that multiplied by 5 give us a total of 35 triangles:

Case 1:

Case 2:

Case 3:

Case 4:

Case 5:

Case 6:

Case 7: