ArchiveShow me a random puzzle
Most recent collections
Sunday Afternoon Maths LXVIIColoured weights
Not Roman numerals
Advent calendar 2018
Sunday Afternoon Maths LXVICryptic crossnumber #2
Sunday Afternoon Maths LXVCryptic crossnumber #1
Square and cube endings
List of all puzzles
Tagsprime numbers triangle numbers circles dates hexagons chess coordinates division numbers algebra averages integration shapes taxicab geometry percentages area chocolate graphs indices geometry crosswords perimeter surds lines complex numbers logic mean odd numbers money colouring remainders fractions addition irreducible numbers sport integers quadratics 2d shapes cryptic clues people maths means spheres unit fractions cube numbers regular shapes sums arrows trigonometry routes dodecagons volume perfect numbers rugby chalkdust crossnumber dice sum to infinity calculus 3d shapes wordplay folding tube maps rectangles sequences ave bases scales planes square numbers books ellipses menace triangles cryptic crossnumbers squares probability doubling coins probabilty games grids speed differentiation floors angles crossnumbers parabolas square roots star numbers time multiples cards pascal's triangle partitions factors symmetry palindromes factorials advent shape functions clocks christmas number multiplication digits balancing proportion polygons
Is it equilateral?
Source: Chalkdust issue 07
In the diagram below, \(ABDC\) is a square. Angles \(ACE\) and \(BDE\) are both 75°.
Is triangle \(ABE\) equilateral? Why/why not?
The number of degrees in one internal angle of a regular polygon with 360 sides.
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?
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.