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anonymous
 one year ago
A 30ft cable is suspended between the tops of two 20ft poles on the level ground. The lowest point of the cable is 5ft above the ground.What is the distance between the two poles?
anonymous
 one year ago
A 30ft cable is suspended between the tops of two 20ft poles on the level ground. The lowest point of the cable is 5ft above the ground.What is the distance between the two poles?

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mathmate
 one year ago
Best ResponseYou've already chosen the best response.0Draw a diagram: dw:1437334323698:dw If the cable is 30' long, what distance separates the two poles?

campbell_st
 one year ago
Best ResponseYou've already chosen the best response.1I would do it this way dw:1437334277446:dw the x axis is the directrix, so the focal length is 5 units a standard form of the parabola that uses focal length and directrix is \[(x  h) = 4a(y  k)\] where (h, k) is the vertex and a is the focal length so you have h = 0, k = 5 and a = 20 so the equation becomes \[(x  0)^2 = 4 \times 5 \times (y  5)\] or \[x^2 = 20(y 5)\] so substitute the height of the pole, y = 20 into the equation and solve for x. this distance will be the perpendicular from the yaxis to the pole when you get the answer, double it to get the distance between the poles

campbell_st
 one year ago
Best ResponseYou've already chosen the best response.1oops a couple of mistakes the standard form is \[(x  h)^2 + 4a(y  k)\] h = 0, k = 5 and a = 5 dw:1437335137953:dw substituting \[x^2 = 4 \times 5 \times (y  5)\] or \[x^2 = 20(y  5)\] now substitute y = 20 and solve for x don't forget to double it

mathmate
 one year ago
Best ResponseYou've already chosen the best response.0dw:1437335569990:dw

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0im confuse @campbell_st

campbell_st
 one year ago
Best ResponseYou've already chosen the best response.1Well I'd say f you hang a wire between 2 pole, then you would have a parabola and I then when about finding the equation of the parabola which I gave you as \[x^2 = 20(y  5)\] if the height of the pole is 20 then let y = 20 and substitute it into the equation

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0i did 205=15*20=300

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0do i have to find the square root of 300

campbell_st
 one year ago
Best ResponseYou've already chosen the best response.1that's correct, the distance from the yaxis to the pole is \[x = \sqrt{300} ~~or~~x = 10\sqrt{3}\] since the y axis is in the middle of the poles, double it to find the total distance

campbell_st
 one year ago
Best ResponseYou've already chosen the best response.1so that's how I'd do the question, I have no idea what you have been taught or what topic the question is from. So I don't know if this solution is something you'd be expected to show

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0its a summer packet for the intro of geometry

campbell_st
 one year ago
Best ResponseYou've already chosen the best response.1ok, I solved it using algebra and assumes the wire forms a parabola when hung between the poles
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