Question

Help please?? 50 points!

Answer 1

The triangle ABC and the triangle BCD are similar, therefore


`(3+9)/(x)=(x)/(9)\ \ \ |cross\ multiply\\\\x^2=12\cdot9\\\\x^2=108\to x=√(108)\\\\x=√(36\cdot3)\\\\x=√(36)\cdot\sqrt3\\\\\boxed{x=6\sqrt3}`

Answer 2

`6 √(3)`
is the correct answer