Question 138207
You serve a tennis ball from one end of a tennis court, 39 ft from the net. You hit the ball at 9 feet above the ground. It travels in a straight path down the middle of the court, and just clears the top of the 3-ft net. How far from the net does the ball land? 

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Draw the picture.
You should see two right triangles.
The larger has height= 9 ft
The smaller has height = 3 ft
The larger has base 39+x ft
The smaller has base x ft.
The triangles are similar.
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EQUATION:
9/(x+39) = 3/x
Cross-multiply to get:
9x = 3x + 117
6x = 117
 x = 19.5 ft (the ball will land 19.5 ft from the net)
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Cheers,
Stan H.