Question

please help
Find the value of x. Round the answer to the nearest tenth, if needed.

A.9
B.18.9
C.22
D.32.1

Answer 1

its D              does your work need to be shown?

Answer 2

$\Delta ADC\sim\Delta CDB\\\\therefore\\\\\dfrac{21}{x}=\dfrac{x}{49}\ \ \ \ |cross\ multiply\\\\x\cdot x=21\cdot49\\\\x^2=21\cdot49\to x=\sqrt{21\cdot49}\\\\x=7\sqrt{21}\to x\approx32.1$

Answer: D. 32.1