Answer:
Answer: 
 
 x = √70 
 
Step-by-step explanation: 
 
The triangles shown are all similar, so the corresponding sides are proportional. 
 
 hypotenuse/long side = x/7 = (7+3)/x 
 
Cross-multiplying gives ... 
 
 x^2 = 7(10) 
 
 x = √70 
 
_____ 
 
You will note that the value of x (the long side) is the geometric mean of the long segment and the whole hypotenuse. 
 
A similar "geometric mean" relation holds for the short side: 
 
 BC = √(CD·CA) 
 
There is yet another "geometric mean" relation that holds for the altitude: 
 
 BD = √(CD·AD)
Explanation:
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