Similarity ratios

Key Notes :

If two triangles are similar, their similarity ratio is the ratio between a side length in the first triangle and the corresponding side length in the second triangle.

Learn with an example

△XYZ ~ △DEF.

Find the ratio of a side length in △XYZ to its corresponding side length in △DEF

Simplify your answer and write it as a proper fraction, improper fraction, or whole number.

Choose any side in △XYZ and the corresponding side in △DEF . Then, find the ratio of the side lengths.

For example, you can use XY and DE .

XY / DE = 2/8 = 1/4

△QRS ~ △HFG.

Find the ratio of a side length in △QRS to its corresponding side length in △HFG

Simplify your answer and write it as a proper fraction, improper fraction, or whole number.

Choose any side in △QRS and the corresponding side in  △HFG . Then, find the ratio of the side lengths.

For example, you can use RS and FG .

RS / FG = 3/1 = 3.

△FGH ~ △UVW.

Find the ratio of a side length in △FGH to its corresponding side length in △UVW

Simplify your answer and write it as a proper fraction, improper fraction, or whole number.

Choose any side in  △FGH and the corresponding side in △UVW . Then, find the ratio of the side lengths.

For example, you can use GH and VW.

GH / VW = 1/5.

Let’s practice!