mscroggs.co.uk
mscroggs.co.uk

subscribe

Puzzles

Is it equilateral?

In the diagram below, \(ABDC\) is a square. Angles \(ACE\) and \(BDE\) are both 75°.
Is triangle \(ABE\) equilateral? Why/why not?

Show answer

17 December

The number of degrees in one internal angle of a regular polygon with 360 sides.

Ticking clock

Is there a time of day when the hands of an analogue clock (one with a second hand that moves every second instead of moving continuously) will all be 120° apart?

Show answer & extension

Tags: angles, time

Dodexagon

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

Three squares

Source: Numberphile
The diagram shows three squares with diagonals drawn on and three angles labelled.
What is the value of \(\alpha+\beta+\gamma\)?

Show answer & extension

Archive

Show me a random puzzle
 Most recent collections 

Advent calendar 2019

Sunday Afternoon Maths LXVII

Coloured weights
Not Roman numerals

Advent calendar 2018

Sunday Afternoon Maths LXVI

Cryptic crossnumber #2

List of all puzzles

Tags

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

Archive

Show me a random puzzle
▼ show ▼
© Matthew Scroggs 2012–2020