Question 778533: two fishing boats depart a harbord at the same time, one traveling east, the other south. the eastbound boat travels at a speed 3 mi/h faster than the southbound boat. after two hours the boats are 30 mi apart. what is the speed of the boat going south?
Answer by lwsshak3(11628)   (Show Source):
You can put this solution on YOUR website! two fishing boats depart a harbord at the same time, one traveling east, the other south. the eastbound boat travels at a speed 3 mi/h faster than the southbound boat. after two hours the boats are 30 mi apart. what is the speed of the boat going south?
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let x=speed of southbound boat
x+3=speed of eastbound boat
distance=speed*traveling time
after 2 hrs:
southbound boat traveled 2x
eastbound boat traveled 2(x+3)=2x+6
you are working with a right triangle with legs of 2x and 2x+6 and hypotenuse=30
By the pythagorean theorem:
(2x)^2+(2x+6)^2=30^2
4x^2+4x^2+24x+36=900
8x^2+24x-864=0
x^2+3x-108=0
(x+12)(x-9)=0
x=-12 (reject, x>0)
or
x=9
speed of southbound boat=9 mph
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