Question 1030381: Jesse and Dawn were out in their rowboat one day,and Jesse spied a water lily. Knowing that Dawn liked a mathematical challenge, Jesse announced that with the help of the plant it was possible to calculate the depth of the water under the boat. While Dawn held the top of the plant, which is originally 10 inches above the water surface, Jesse gently rowed the boat five feet, which forced Dawn's hand to the water surface. How deep was the water?
Answer by addingup(3677)   (Show Source):
You can put this solution on YOUR website! First of all, convert all the numbers in the problem into the same units
5 ft = 60 in.
In the boats original position, let the length of the plant underwater be x, making the length of the entire plant x+10.
As the boat moved 60 inches, the length of the plant becomes the hypotenuse of a right triangle having legs of x and 60. So use the Pythagorean Theorem.
x^2+60^2 = (x+10)^2
x^2+3600 = x^2+20x+100 (x+10)(x+10)
3600 = 20x + 100
3500 = 20x
175 = x
So the depth of the water below the water lilly is 175 inches or 14 feet 7 inches.
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