Categories
Intermediate

The three rights

A trapezium containing three right angles is split in two. What is the proportion of the areas yellow : blue?

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Advanced

The fallen pine

Two congruent isosceles triangles and three lines. Prove triangle AEF is also isosceles.

Categories
Beginner

The color fan

Two congruent rectangles share a vertex. Given that the three coloured areas are equal, what is the width x?

Categories
Intermediate

The right angle

Two triangles inside a quarter circle. What is their area proportion?

Categories
Intermediate

The triangle quartet

A square is divided into four triangles. The red area equals the blue area. What is the angle α?

Categories
Intermediate

The corner stone

Four squares inside another square. What fraction is yellow?

Categories
Advanced

The bigger picture

In a small square two perpendicular lines are drawn. A larger parallel square is constructed as shown. Prove it is a scaled copy of the smaller square but rotated 90° anticlockwise.

Categories
Intermediate

La Flèche Wallonne

A triangle is divided in four. What is the black area?

Categories
Beginner

The cross

A rectangle of height 2 is crossed by two line segments at right angles. What is its width?

Categories
Intermediate

The navel orange

Two quarter circles and a semicircle inside a circle. What fraction of the circle is shaded by the semicircle?