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September 22, 2014

September 22, 2014

Posted by **jane** on Monday, October 24, 2011 at 9:14am.

- math -
**Jai**, Monday, October 24, 2011 at 10:05amrecall that speed is distance travelled over time.

let x = speed of the other car.

then we set-up the equation.

when you draw the directions they're travelling, you will form a right triangle. thus recall that in a right triangle, the hypotenuse (in this the the distance between them which is 100 miles) is given by the Pythagorean theorem:

c^2 = a^2 + b^2

we equate distances:

100^2 = (40*2)^2 + (2x)^2

10000 = 80^2 + 4x^2

10000 - 6400 = 4x^2

3600 = 4x^2

x^2 = 900

x = 30 mph

hope this helps~ :)

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