Angles - points, lines and parallel lines

Weekly Problem 35 - 2009
Two equilateral triangles have been drawn on two adjacent sides of a square. What is the angle between the triangles?

Explore patterns based on a rhombus. How can you enlarge the pattern - or explode it?

Which hexagons tessellate?

Can you use LOGO to create a systematic reproduction of a basic design? An introduction to variables in a familiar setting.

This diagram has symmetry of order four. Can you use different geometric properties to find a particular length?

This investigation explores using different shapes as the hands of the clock. What things occur as the the hands move.

What is the sum of the angles of a triangle whose sides are circular arcs on a flat surface? What if the triangle is on the surface of a sphere?

Weekly Problem 16 - 2007
Can you figure out how far the robot has travelled by the time it is first facing due East?

P is a point inside a square ABCD such that PA= 1, PB = 2 and PC = 3. How big is angle APB ?

Six circles around a central circle make a flower. Watch the flower as you change the radii in this circle packing. Prove that with the given ratios of the radii the petals touch and fit perfectly.