This set includes 1 large yellow equilateral triangle with black lines along all three sides, and 10 obtuse-angled isosceles triangles in total:

• 2 red triangles with a black line on the longer side
• 2 gray triangles with a black line on one of the equal sides
• 6 yellow triangles:
• 3 with black lines on two equal sides
• 3 with a black line on the longer side

This educational tool helps children learn how combining different triangles can form four-sided shapes.