What do you notice? Why does this happen? Will it […]
You will need a cut-out paper circle (about 12cm diameter).
Use a circle that does not show the centre. Fold your circle along a diameter. Mark the ends A and B. Now unfold your circle and then fold again along a different diameter and mark the […]
This shape is an equilateral triangle sitting on top of a square.
What is the radius of the circle that circumscribes the shape?
Click here for a hint if you need one to get started.
This problem is adapted from the […]
This diagram shows a proof.
Look carefully. Can you see three squares?
Assuming that they are squares, can you prove that four of the triangles are congruent?
Can you explain the proof?
The second diagram shows a well known proof using similar triangles.
The diagram shows three angles a, b and c.
How many ways can you prove that a + b = c?
What other interesting properties can you find?
When this activity was originally published on NRICH, two boys from Madras School in St Andrew’s, Scotland sent […]