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

A. AC = 14 cm; CE = 8 cm
B. AC = 12 cm; CE = 7 cm
C. AC = 10 cm; CE = 5 cm
D. AC = 5 cm; CE = 10 cm

Since BC is parallel to DE triangles ABC and ADE are similar What are the lengths of the unknown sides A AC 14 cm CE 8 cm B AC 12 cm CE 7 cm C AC 10 cm CE 5 cm class=

Respuesta :

Answer:

C

Step-by-step explanation:

Step 1: find BC

Given Triangles ABC and ADE are similar,

[tex]\frac{AB}{AD}[/tex] = [tex]\frac{BC}{DE}[/tex]

BC = [tex]\frac{AB}{AD}[/tex] x DE

= [tex]\frac{8}{8 + 4}[/tex] 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)