SOLUTION: A car leaves an intersection traveling west. Its position 4 sec later is 18 ft from the intersection. At the same time, another car leaves the same intersection heading north so th

Question 624781: A car leaves an intersection traveling west. Its position 4 sec later is 18 ft from the intersection. At the same time, another car leaves the same intersection heading north so that its position 4 sec later is 29 ft from the intersection. If the speeds of the cars at that instant of time are 7 ft/sec and 11 ft/sec, respectively, find the rate at which the distance between the two cars is changing.
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
A car leaves an intersection traveling west. Its position 4 sec later is 18 ft from the intersection. At the same time, another car leaves the same intersection heading north so that its position 4 sec later is 29 ft from the intersection. If the speeds of the cars at that instant of time are 7 ft/sec and 11 ft/sec, respectively, find the rate at which the distance between the two cars is changing.
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The distances from the intersection are not relevant if they leave the intersection at the same time. It's a Pythagorean calculation.

r =~ 13.04 ft/sec
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"instant of time" is redundant and fails at pedantry. instant is sufficient, as instants always implies time.
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Also, "respectively" serves no purpose.
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Math tutor, grammar nazi.

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