Question

Given two similar triangles, what would you need to know to find an unknown length? How would you find that unknown length?

Answer 1

There is a pattern with the ratios of corresponding sides. You can see that the measurement of each side of the first triangle divided by two is the measure of the corresponding side of the second triangle. Use patterns like this to problem solve the length of missing sides of similar triangles.

Answer 2

From two similar triangles, the length of an unknown side can be found using the following steps:

• Let the two similar triangles be A and B.
• Determine the sides of A corresponding to the sides of B.          
• The smallest side of A will correspond to the smallest side of B.
• Similarly, the largest side of A will correspond to the largest side of B.
• According to a theorem of similar triangles;

"The ratio of the corresponding sides of the similar triangles are equal"

• Consider the known corresponding sides of A and B.
• Find out their ratio.
• Let it be equation 1.
• Now consider the unknown side and its known corresponding side in the other triangle.
• Find their ratio.
• Let it be equation 2.
• Now equate the equations 1 and 2.
• We get the value of the unknown side.