Categories
Intermediate

The triple airbag

A triangle containing three tangent semicircles with diameters a, b and c. Three line segments pass through the red tangency points. What is the triangle perimeter?

Categories
Intermediate

At navel level

Two equilateral triangles share a vertex. The centre of the larger one is aligned with the midpoint of a side of the smaller one. What is green : red?

Categories
Intermediate

The common focus

A parabola, its symmetry axis and a tangent. Yellow connects the focus to the intersection point. Red connects the focus to the tangency point. What’s yellow : red?

Categories
Beginner

The purple hat

A circle with three tangents forming an isosceles triangle. Two tangency points are shown. What is the proportion green : red?

Categories
Intermediate

Two hemispheres

A triangle with its circumscribed circle and a smaller intersecting circle. The two intersection points and the circumcentre are shown. What’s the proportion red : green?

Categories
Intermediate

The wedge

A trapezium with its inscribed circle. Two tangency points are shown. What’s red / blue – yellow / green?

Categories
Beginner

The green deal

Three squares, one of which has a side length of 2. What is the green area?

Categories
Advanced

Slightly skewed

Two overlapping equilateral triangles with side lengths 1. What is the total red length?

Categories
Beginner

Overhanging rock

A rectangle with three line segments. What’s the proportion red : yellow?

Categories
Intermediate

Emerging from water

Two squares and an extended side. What’s red : green : pink?