Question

Help me please and thank you

Answer 1

? = 5

Explanation:

Look at the picture.

ΔADC and ΔCDB are similar (AAA). Therefore corresponding sides are in proportion

`(15)/(x)=(x)/(20-15)\\\\(15)/(x)=(x)/(5)`

cross multiply

`x^2=(15)(5)\\\\x^2=75\to x=√(75)\\\\x=√(25\cdot5)\\\\x=√(25)\cdot\sqrt5\\\\x=5\sqrt5`