Question

Since BC is parallel to DE, triangles ABC and ADE are similar. What are the lengths of the unknown sides?

Answer 1

Answer:

C

Step-by-step explanation:

Step 1: find BC

Given Triangles ABC and ADE are similar,

$\frac{AB}{AD}$ = $\frac{BC}{DE}$

BC = $\frac{AB}{AD}$ x DE

= $\frac{8}{8 + 4}$ x 9

= 6 cm

Step 2: use Pythagorean theorem to find AC and / or AE

Consider triangle ABC,

by Pythagorean theorem,

AB² + BC² = AC²

AC² = 6² + 8² = 100

AC = √100 = 10 (answer... we can see that C is the only one with AC=10.

Step 3: Verify.. even though we know that it is C because AC  = 10,  you can verify that the ansewer is correct by finding CE and confirming that CE=5

By using similar triangles ABC and ADE,

AC/AE = AB / AD

AE = AD/AB x AC = 12/8 x 10 = 15

CE = AE - AC = 15 - 10 = 5 (answer confirmed)