Lesson 11 of 14
Which test decides it
Show on a big screenA card lists measurements for two triangles. Are they similar? Match the corners first.
Three tests
Use AA, SSS or SAS to decide if two triangles are similar.
Match the corners first. Two matching angles give AA. Three side ratios give SSS. Two side ratios with the angle between them give SAS.
| Test | Needs |
|---|---|
| AA | Two matching angles |
| SSS | All three side ratios equal |
| SAS | Two side ratios and the angle between them |
Read the figure
The 50° corners are P and Z. The 60° corners are R and Y. So P pairs with Z, and R pairs with Y. That leaves Q paired with X. Both third angles are 70°. AA decides it. Triangle PQR is similar to triangle ZXY.
Sometimes no test applies. One angle pair alone is not a test. Two side ratios without the angle between them are not a test.
Pick the test for seven cards.
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Try the lab to finish this lesson.