Question

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

Answer 1

Explanation:

In similar triangles, corresponding sides are in same ratio.

`(BC)/(EF)=(AB)/(DE)\\\\\\(x)/(5)=(21)/(7)\\\\\\x=(21)/(7)*5\\\\\\x= 3*5 =15`

x = 15

Answer 2

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

`(BC)/(AB) =(EF)/(DE) \\\\(x)/(21) =(5)/(7) \\7x = 21*5\\7x = 105\\x = 15\\`

Hope that helps!