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