7-4
7-4 . Similar Triangles. F. C. A. B. D. E. Two polygons are similar if and only if their corresponding angles are congruent and the measures of their corresponding sides are proportional. Similar Polygons. ~ means “is similar to”.
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7-4 Similar Triangles
F C A B D E Two polygons are similar if and only if their corresponding angles are congruent and the measures of their corresponding sides are proportional. Similar Polygons ~ means “is similar to”
If two angles of one triangle are congruent (equal) to two angles of another triangle, then the triangles are similar. Note: If you know two angles, the third angle is not negotiable AA Similarity Postulate
Example 1: • Example 2: C 60º F 62º 58º 60º 50º 40º G H D E 61º 59º YES- 2 angles of triangle CDE are congruent to 2 angles of triangle FHG NO- only 1 angle is congruent in both triangles Examples: Tell whether the triangles are similar or not. *You need two angles to be congruent to prove the triangles are similar!
*If two triangles share an angle, then they share a congruent angle y y 4 4 6 6 3 2 y+3 4+2=6 x x Example 3: Find the values of x and y.
M J ΔLMN N L K Example 4: Complete the following statement: ΔJKN ~ _______ *Make sure you match up corresponding angles *It matters how you name your triangle!!
