Similar Lengths Flashcards

All 5 cards in this deck

What are the steps to find a missing length on the larger of two similar triangles?

e.g. $5$ cm corresponds to $20$ cm; find the side matching $4$ cm

1. Divide a pair of corresponding sides: $20\div5=4$
2. Multiply the known side by the scale factor: $4\times4=16$ cm.

How do you find a missing length on the smaller of two similar shapes?

e.g. scale factor $1.5$, corresponding length on the larger shape $15$ cm

Divide by the scale factor: $15\div1.5=10$ cm.

In two similar triangles, how do you decide which sides correspond?

e.g. triangles $ABC$ and $ADE$ with $BC$ parallel to $DE$

Sides in the same position relative to the equal angles correspond: $AB$ with $AD$, $AC$ with $AE$, $BC$ with $DE$.

True or false? To find a missing length in similar shapes you add on the difference between a pair of corresponding sides.

False. You multiply (or divide) by the scale factor, because similar lengths are in the same ratio.

True or false? The scale factor from the larger shape to the smaller similar shape is less than $1$.

True. It is a reduction, e.g. a scale factor of $0.25$ instead of $4$.