# Triangles ABC and DEF are similar. If DE = 9, EF = 7, and AB = 4.5, what is BC?

##### 1 Answer
Nov 23, 2016

$B C = 3.5$

#### Explanation:

If two given triangles are similar i.e. DeltaABC~Delta DEF. then

$\angle A = \angle D$, $\angle B = \angle E$, $\angle C = \angle F$ and $\frac{A B}{D E} = \frac{B C}{E F} = \frac{C A}{F D}$

As $D E = 9$, $E F = 7$, and $A B = 4.5$, we have

$\frac{4.5}{9} = \frac{B C}{7}$ and

$B C = 7 \times \frac{4.5}{9} = \frac{7}{2} = 3.5$