The sum of a convergent geometric series – triangles Whiteboard exercise Play

The sum of the angles in a triangle Animation Play

The sum of the angles in the triangle Animation Play

The sum of the angles in the triangle Whiteboard exercise Play

The sum of the interior angles of a quadrilateral – proof Animation Play

The symmetry of triangles Whiteboard exercise Play

The tangent Whiteboard exercise Play

The tangent Student activity Play

The tangent and coordinates of the points Animation Play

The tangent of an arbitrary angle Student activity Play

The tangent theorem – solving problems Whiteboard exercise Play

The triangle Whiteboard exercise Play

The triangle Student activity Play

The triangle inscribed in a circle Whiteboard exercise Play

The triangle under enlargement Animation Play

The triangles under enlargement Whiteboard exercise Play

Theorem – assumptions and claim Student activity Play

Theorem – assumptions and claim Whiteboard exercise Play

Theorems and their assumptions in geometry Student activity Play

Transform a triangle into a rectangle Student activity Play

Transform a triangle into a rectangle Simulation Play

Transformation of a triangle Animation Play

Transformations Student activity Play

Translation, rotation, reflection and symmetry Animation Play

Trapezium Student activity Play