The concept of congruence, or equality in measure, is very common in geometry courses. In earlier topics, you have explored congruent segments, congruent lines, and congruent triangles. When it comes to triangles, not all are congruent or equal in size and shape. Some triangles have nothing in common, and others share some attributes. Triangles that are the same shape but different size are called similar triangles. In this topic, you will explore what attributes two triangles must have for them to be similar. You will also study postulates that can help you more easily identify similar triangles.

Essential Questions

• How can you use the SSS Similarity Theorem to prove triangles are similar?
• How can you use the SAS Similarity Theorem to prove triangles are similar?
• How can you use the AA Similarity Postulate to prove triangles are similar?

 

Warm-Up

Before you try your hand at using similarity postulates in this topic, take a moment to refresh your memory of working with ratios in this non-graded interactivity. Click the player button to get started.