Categories
Beginner

Out of the box

Two squares and two given areas. What’s the total area?

Categories
Intermediate

The spotlight

A right triangle with two cevians. What’s the angle α?

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Advanced

The lemon slice

A semicircle is inscribed in a quarter circle. What is the minimal yellow fraction?

Categories
Intermediate

Connecting the dots

Three squares share three vertices which form a right triangle. Their centres are connected to form another triangle of which one side is given. What’s the blue area?

Categories
Intermediate

Between the bars

Two parallel lines support two rectangles. Prove they have equal area.

Categories
Beginner

Mount Fuji

An equilateral triangle inscribed in a circle is divided by a diameter parallel to one of its sides. What is the proportion light : dark blue?

Categories
Advanced

The Magdeburg hemispheres

A square containing a circle and two semicircles, all three having the same radius. What fraction is purple?

Categories
Beginner

Band-Aid

Five unit squares inside a larger square. What is the total area?

Categories
Intermediate

The axe head

A tetrahedron with given vertex coordinates. What is its volume?

Categories
Intermediate

The sleeping bag

A semicircle containing a circle. One line segment is tangent to the circle and connects to the semicircle centre. The chord connects two tangency points. What fraction is blue?