# MO SK/CZ Z9–I–3

John had the ball that rolled into the pool and it swam in the water. Its highest point was 2 cm above the surface. Diameter of circle that marked the water level on the surface of the ball was 8 cm. Determine the diameter of John ball.

Result

D =  10 cm

#### Solution:

$r^2=(8/2)^2+(r-2)^2 \ \\ r^2=16+r^2-4r+4 \ \\ 0=20-4r \ \\ r=20/4=5 \ \text{cm} \ \\ D=2 \cdot \ r=2 \cdot \ 5=10 \ \text{cm}$ Our examples were largely sent or created by pupils and students themselves. Therefore, we would be pleased if you could send us any errors you found, spelling mistakes, or rephasing the example. Thank you!

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