Categories
Beginner

The three day stubble

A regular pentagon and a square share two vertices. What’s the angle α?

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Advanced

It’s complicated

A circle, a semicircle and several triangles. The black points are tangency points. What proportions have the line segments a : r : b?

Categories
Advanced

The odd couple

A semicircle with two inscribed triangles The tangency points of the incircle of the bigger triangle are shown. What is the triangle area proportion orange : blue?

Categories
Intermediate

Parallel universes

Two straight lines are specified by y=a+cx and y=b+cx, respectively, where b≥a. What’s the distance d between them in terms of a, b and c?

Categories
Advanced

Blazing hot

A circle inscribed in a triangle inscribed in a semicircle. The line segment through two tangency points meets a radius at the semicircle circumference. What is the angle α?

Categories
Beginner

Trinity

Three squares are placed as shown. What fraction of the total area is green?

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Intermediate

The turning point

Two isosceles triangles share a vertex. What is the maximum of their area proportion red/green?

Categories
Intermediate

The kingsize bed

A rectangle with an inscribed right triangle. What is ac/bd?

Categories
Intermediate

The obstructed view

A rectangle and two squares of side length a and b respectively. What is the red area in terms of a and b?

Categories
Intermediate

Mickey Mouse

Three regular pentagons and two extended sides. What fraction of the total area is red?