Two circles support a triangle. Prove it is equilateral.

# Month: February 2021

## The magic mirror

You are standing in front of a mirror. Your shoulder width is 50 cm and your eyes are 6 cm apart. What is the minimum mirror width for a stereo view of yourself?

## Daft Mouse

A square with two attached regular pentagons. A side and a diagonal are extended. What’s the angle?

## The colour of spring

A square with a diagonal and a right angle. Two areas are given. How large is the pink area?

## The monk’s hood

Two similar triangles inside a semicircle. What’s the angle?

## Mars rover has landed

Two semicircles and two right triangles. What fraction of the large triangle does the small one cover?

## Two hefty volumes

Two congruent rectangles inscribed in a square. What fraction of the area is blue?

## Ménage à trois

Three equilateral triangles of which two are congruent. Are the three points collinear?

## The flying banner

A triangle with a quadrilateral that covers half its area. What is the angle?

## Mini and Maxi

Two squares of area 1 and 4 are inscribed in their own triangle and placed as shown. What fraction is coloured?