Definition:Similar Triangles

Definition

Similar triangles are triangles whose corresponding angles are the same, but whose corresponding sides may be of different lengths.

Thus $\triangle ABC$ is similar to $\triangle DEF$:

$\angle ABC = \angle EFD$

$\angle BCA = \angle EDF$

$\angle CAB = \angle DEF$

Also see

• Equiangular Triangles are Similar
• Triangles with Two Equal Angles are Similar (a stronger result)

• The general definition of Similar Figures

• Results about similar triangles can be found here.

Sources

• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): similar
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): similar