Skip over navigation
Triangles' Triangle
Age 11 to 14
ShortChallenge Level 
The perimeter of the large triangle is 24 cm. What is the total length of the black lines used to draw the figure?
If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.
This problem is taken from the UKMT Mathematical Challenges.
You can find more short problems, arranged by curriculum topic, in our short problems collection.
You may also like
Is There a Theorem?
Draw a square. A second square of the same size slides around the first always maintaining contact and keeping the same orientation. How far does the dot travel?
Coins on a Plate
Points A, B and C are the centres of three circles, each one of which touches the other two. Prove that the perimeter of the triangle ABC is equal to the diameter of the largest circle.
Smaller and Smaller
Can you predict, without drawing, what the perimeter of the next shape in this pattern will be if we continue drawing them in the same way?