Similar triangles have equal corresponding angles and proportional corresponding sides. Match the vertices before setting up a proportion.
Key Rules
Two equal corresponding angles are enough to establish triangle similarity.
Use the same small-to-large or large-to-small order in each ratio.
If side lengths scale by k, areas scale by k².
Common Mistakes to Avoid
Pairing sides by their position on the page instead of their corresponding angles.
Using a side-length scale factor directly for area.
SAT Strategy Tips
→Write the triangle names in corresponding vertex order.
→Mark the longest sides first when the diagram’s orientation is confusing.
Example Question
In two similar triangles, a 4-unit side corresponds to a 6-unit side. Another side of the smaller triangle is 8 units. How long is the corresponding larger side?
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