Proportions and Similar Triangles

Triangle Proportionality Theorem: If a line is parallel to one side of a triangle and intersects the other two sides, then it separates the sides into segments of proportional lengths.

Converse of the Triangle Proportionality Theorem:

If a line intersects two sides of a triangle and separates the sides into corresponding segments of proportional lengths, then the line is parallel to the third side.

Special Segments of Similar Triangles:

If two triangles are similar, then the measures of the corresponding altitudes are proportional to the measures of the corresponding sides.

If two triangles are similar, then the measures of the corresponding angle bisectors of the triangles are proportional to the measures of the corresponding sides.

If two triangles are similar, then the measures of the corresponding medians are proportional to the measures of the corresponding sides.

Proportional Perimeters Theorem: If two triangles are similar, then the perimeters are proportional to the measures of corresponding sides

Learn more about proportions and similar triangles by reading the explanation below.

Proportions and Similar Triangles


Practice: Identify and use the relationships between proportional parts of triangles in answering the exercises below.

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