Geometry

Ruler with two parallel edges
Like a Sangaku tangent circles in a circle
Not a Sangaku tangent incircles in a split triangle
Sangaku again 3 circles and a triangle : an amazing perpendicular !
Grazing with 3D constraints on the rope
Even more Sangaku four equal circles in an equilateral triangle
More Sangaku three equal circles in triangle divided in 3
Three cercles Inscribe 3 equal tangent circles in a triangle
Straightedge alone Constructions with just the straightedge
Grèbe three squares in a triangle
Woodwork cut a cube, cut a prism
Erased triangle II problem of Cramer-Castillon
5 circles five equal circles in a square
2 circles two equal circles in a triangle
2 rectangles two equal rectangles in a square
Proportions point at distances proportional to x:y:z
Balance Balance of a picture, of a floating cube
A rose Areas in a rose
Triangles Construct a triangle, given etc...
In half Split a triangle in two parts with equal area and perimeter
Kashikar Line intersecting 2 circles in 3 equal segments
Miquel circle Construct triangle through 3 points
Inscribed triangle III Smallest similar triangle inscribed in triangle
A Sangaku Classical Sangaku with 2 squares and a circle in a circle
A strange butterfly An extension to the Butterfly theorem
Inscribed II Construct a triangle in a triangle
Construct Construct a triangle, given...
Segments Use of a collapsing compass
Matriochkas Sequence of nested triangles
3D Geometric constructions in 3D space
Inscribed triangle Equilateral triangle inscribed in a triangle
Max triangle II Max triangle on ellipse
The pizza II Sharing a pizza, part II
Tetrahedron Integer point inside a tetrahedron
Steiner Steiner chain of circles
Malfatti like Three circles in a curved triangle
The tower Height of tower from angles
Apollonius Circles touching three others
Heron Heron formula and the like
Arbelos A Sangaku like problem
Not Pythagora but same area
Bicentric Bicentric quadrilaterals
Inside a cube What can be found inside a cube
Circles Packing of circles
Compass alone Constructions with compass alone
Dry compass Constructions with a dry compass
Distance Shortest distance between 2 trains
The rockets N rockets aiming at each other
The ant Shortest path
Dissections Dissections
Shares Sharing a triangle in N
The well Splitting a triangle in two equal parts
Fence Sharing a triangle by shortest fence
Not enough data Apparently not enough...
Triangle A point in a triangle with given distances
Square A point in a square with given distance
The pizza Sharing a pizza
Maximum triangle Largest inscribed triangle
Maximum Polygon Largest n-gon inscribed in a square
The half-cylinder A half-cylinder on a slope
Erased square Find a square knowing 4 points
Erased triangle Find a triangle knowing 3 points
The garden Patrolling a triangular garden
The keep Annulus area
Minimum triangle Smallest triangle
4 lines Find a line cut in 3 equal parts by 4 given lines
ZigZag Circle cut by a ZigZag
Camping Shortest distances to river and wood
Fagnano Smallest inscribed triangle