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?