12 December

These three vertices form a right angled triangle.
There are 2600 different ways to pick three vertices of a regular 26-sided shape. Sometime the three vertices you pick form a right angled triangle.
Today's number is the number of different ways to pick three vertices of a regular 26-sided shape so that the three vertices make a right angled triangle.


Show answer


In the diagram, B, A, C, D, E, F, G, H, I, J, K and L are the vertices of a regular dodecagon and B, A, M, N, O and P are the vertices of a regular hexagon.
Show that A, M and E lie on a straight line.

Show answer & extension


Show me a random puzzle
 Most recent collections 

Sunday Afternoon Maths LXVII

Coloured weights
Not Roman numerals

Advent calendar 2018

Sunday Afternoon Maths LXVI

Cryptic crossnumber #2

Sunday Afternoon Maths LXV

Cryptic crossnumber #1
Breaking Chocolate
Square and cube endings

List of all puzzles


differentiation palindromes calculus sums division dates colouring volume sum to infinity prime numbers people maths triangle numbers balancing complex numbers remainders proportion coins speed cryptic crossnumbers angles chalkdust crossnumber scales perfect numbers shape circles 2d shapes factorials algebra geometry pascal's triangle rectangles probabilty christmas quadratics dodecagons area floors sequences wordplay coordinates star numbers regular shapes books indices multiplication sport logic cryptic clues taxicab geometry menace integers graphs ave crossnumbers folding tube maps digits 3d shapes probability squares routes integration crosswords partitions planes perimeter surds odd numbers triangles number multiples clocks mean grids irreducible numbers chess factors averages money advent unit fractions spheres ellipses cube numbers games numbers arrows shapes fractions rugby parabolas dice symmetry percentages trigonometry chocolate time doubling addition square numbers means square roots hexagons cards functions bases lines polygons


Show me a random puzzle
▼ show ▼
© Matthew Scroggs 2019