Answer:
[tex] x = \sqrt{30} [/tex]
Step-by-step explanation:
By Geometric mean property:
[tex]BD = \sqrt{3 \times 7} \\ BD = \sqrt{21} \\ by \: pythagoras \: theorem \\ {x}^{2} = { (\sqrt{21}) }^{2} + {(3)}^{2} \\ {x}^{2} = 21 + 9 \\ {x}^{2} = 30 \\ x = \sqrt{30} [/tex]
