Similarity and congruence

There are 62 NRICH Mathematical resources connected to Similarity and congruence
Another Triangle in a Triangle
problem

Another Triangle in a Triangle

Age
16 to 18
Challenge level
filled star filled star empty star
Can you work out the fraction of the original triangle that is covered by the green triangle?
Same length
problem

Same length

Age
11 to 16
Challenge level
filled star filled star empty star
Construct two equilateral triangles on a straight line. There are two lengths that look the same - can you prove it?