Question 208791This question is from textbook
: Bicyclists Hilary and Eric leave the same point Q at the same time at right angles. Hilary travels four mi/h faster than Eric. After 4 hours they are 80 miles apart. Find the speed of each.
This question is from textbook
Answer by RAY100(1637)   (Show Source):
You can put this solution on YOUR website! Distance = Velocity * Time
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Eric velocity =e,,,,,Eric distance = 4e
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Hilary velocity = (e+4),,,,,Hilary distance = 4(e+4) = (4e +16)
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As they are perpendicular, Pythagorean Theorem, c^2 = a^2 + b^2,,,or
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80^2 = (4e)^2 + (4e+16)^2 = 16e^2 + 16e^2 +128e +256
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32e^2 +128e -6144 =0,,,,,,,80^2 -256 = 6144
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divide thru by 32
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e^2 +4e -192 =0
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(e+16)(e-12)=0
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e= 12 mph, -16(not realistic)
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h= 12+4 = 16 mph
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Check,,,(4*12)^2 +(4*16)^2 =80^2,,,,ok
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