Triangle wave
Geometry
Level
2
What is the area shaded in yellow? The blue triangles are isosceles right triangles of equal size.
The answer is 432.
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1 solution
Base of triangle is 72 / 9 = 8.
Half of base = 4.
Right isosceles triangles have acute angles of 45 degrees so height = half of base.
Height = 4.
Area of blue triangle = .5 x 8 x 4 = 16.
Total blue area = 16 x 9 = 144.
Height of rectangle = 2 x 4 = 8.
Area of rectangle = 72 x 8 = 576.
Yellow area = 576 - 144 = 432.