A floor is covered by a tessellation of equilateral triangles, each having three equal arcs inside it. What proportion of the area of the tessellation is shaded?

The three corners of a triangle are sitting on a circle. The angles are called Angle A, Angle B and Angle C. The dot in the middle of the circle shows the centre. The counter is measuring the size. . . .

What can you say about the angles on opposite vertices of any cyclic quadrilateral? Working on the building blocks will give you insights that may help you to explain what is special about them.

Triangle ABC is isosceles while triangle DEF is equilateral. Find one angle in terms of the other two.

Investigate the different ways of cutting a perfectly circular pie into equal pieces using exactly 3 cuts. The cuts have to be along chords of the circle (which might be diameters).

The graph below is an oblique coordinate system based on 60 degree angles. It was drawn on isometric paper. What kinds of triangles do these points form?

Use the interactivity to investigate what kinds of triangles can be drawn on peg boards with different numbers of pegs.

Show that among the interior angles of a convex polygon there cannot be more than three acute angles.

Is it true that any convex hexagon will tessellate if it has a pair of opposite sides that are equal, and three adjacent angles that add up to 360 degrees?

How can you make an angle of 60 degrees by folding a sheet of paper twice?

Semi-regular tessellations combine two or more different regular polygons to fill the plane. Can you find all the semi-regular tessellations?

Can you explain why it is impossible to construct this triangle?

Can you find all the different triangles on these peg boards, and find their angles?

How many different triangles can you make which consist of the centre point and two of the points on the edge? Can you work out each of their angles?

This article gives an wonderful insight into students working on the Arclets problem that first appeared in the Sept 2002 edition of the NRICH website.

How would you move the bands on the pegboard to alter these shapes?

Billy's class had a robot called Fred who could draw with chalk held underneath him. What shapes did the pupils make Fred draw?

What is the relationship between the angle at the centre and the angles at the circumference, for angles which stand on the same arc? Can you prove it?

Measure the two angles. What do you notice?

More Logo for beginners. Learn to calculate exterior angles and draw regular polygons using procedures and variables.

Creating designs with squares - using the REPEAT command in LOGO. This requires some careful thought on angles

This LOGO Challenge emphasises the idea of breaking down a problem into smaller manageable parts. Working on squares and angles.

Turn through bigger angles and draw stars with Logo.