Question

The figure shows AABC ~ ADEF with side lengths as indicated. What is the value of x?

Answer 1

Answer:

Step-by-step explanation:

In similar triangles, corresponding sides are in same ratio.

$\dfrac{BC}{EF}=\dfrac{AB}{DE}\\\\\\\dfrac{x}{5}=\dfrac{21}{7}\\\\\\x=\dfrac{21}{7}*5\\\\\\x= 3*5 =15$

x = 15

Answer 2

If two triangles are similar, that means their side lengths are proportional, so:

  $\frac{BC}{AB} =\frac{EF}{DE} \\\\\frac{x}{21} =\frac{5}{7} \\7x = 21*5\\7x = 105\\x = 15$

Hope that helps!