
58 Chapter 2
similar triangles have the same angles
Similar triangles don’t just look the same
Similarity is a key piece of geometry jargon. If two shapes are similar, then
they don’t just look alike, one is an exact scaled version of the other. This
means that they have the same (equal) angles.
But don’t take our word for it…check that it all adds up:
Line part way up
the triangle
Tick marks to show that
our line is parallel
These triangles are similar. In
geometry terms, we don’t just
mean they kinda look the same.
Similar triangles
don’t have to be
the same way up.
86°
53°
41°
86°
53°
41°
86
o
41
o
53
o
41
o
53
o
86
o
41°
53°
86°
Take a big triangle, and draw
a line part way up the triangle,
parallel with the base.
1
This creates a mini triangle
which shares the angle at the
peak of the big triangle.
2