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alexdok [17]
3 years ago
7

What is the value of X?

Mathematics
1 answer:
Ugo [173]3 years ago
4 0

∆ABC similar to ∆CBD

DB/AC = CB/AB

\frac{x}{7.5}  =  \frac{7.5}{x + 3}  \\ x(x + 3) =  {7.5}^{2}  =  { (\frac{15}{2}) }^{2}  \\  {x}^{2}  + 3x =  \frac{225}{4}  \\ 4 {x}^{2}  + 12x = 225 \\ 4 {x}^{2}  + 12x + 9 = 216 \\  {(2x + 3)}^{2}  = 216 \\ 2x + 3 = 6 \sqrt{6}  \\ x =  - 1.5 + 3 \sqrt{6}

approximately 6.1485

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