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You live near a bridge that goes over a river. The underside of the bridge is an arch that can be modeled with the function y = –0.000471x² + .837x where x and y are measured in feet. How high above the river is the bridge (the top of the arch)? How long is the section of bridge above the arch?
The bridge is about 1,777.07 ft. above the river, and the length of the bridge above the arch is about 888.54 ft.
The bridge is about 371.85 ft. above the river, and the length of the bridge above the arch is about 1,777.07 ft.
The bridge is about 371.85 ft. above the river, and the length of the bri
 one year ago
 one year ago
You live near a bridge that goes over a river. The underside of the bridge is an arch that can be modeled with the function y = –0.000471x² + .837x where x and y are measured in feet. How high above the river is the bridge (the top of the arch)? How long is the section of bridge above the arch? The bridge is about 1,777.07 ft. above the river, and the length of the bridge above the arch is about 888.54 ft. The bridge is about 371.85 ft. above the river, and the length of the bridge above the arch is about 1,777.07 ft. The bridge is about 371.85 ft. above the river, and the length of the bri
 one year ago
 one year ago

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kandsbbfBest ResponseYou've already chosen the best response.0
The bridge is about 1,777.07 ft. above the river, and the length of the bridge above the arch is about 888.54 ft. The bridge is about 371.85 ft. above the river, and the length of the bridge above the arch is about 1,777.07 ft. The bridge is about 371.85 ft. above the river, and the length of the bridge above the arch is about 888.54 ft. The bridge is about 1,777.07 ft. above the river, and the length of the bridge above the arch is about 371.85 ft.
 one year ago

campbell_stBest ResponseYou've already chosen the best response.1
ok... to find the distance spanned by the arch you need to solve it so \[0.00047x^2 + 0.837x = 0... or... x(0.00047x  0.837)\] so x = 0 or 0.837/0.00047 the distance between the points will be the distance spanned. dw:1358113884987:dw
 one year ago

campbell_stBest ResponseYou've already chosen the best response.1
ok... do you know to differentiate..?
 one year ago

campbell_stBest ResponseYou've already chosen the best response.1
ok... do you know how to find the line of symmetry of the curve...?
 one year ago

campbell_stBest ResponseYou've already chosen the best response.1
what answer did you get got the distance spanned by the bridge..?
 one year ago

campbell_stBest ResponseYou've already chosen the best response.1
oops missed a digit it should be 0.837/0.000471 and you should get 1777.07
 one year ago

campbell_stBest ResponseYou've already chosen the best response.1
ok so the parabola is symmetric and the highest point of the arch is on the line of symmetry... do you know how to find the line of symmetry..?
 one year ago

kandsbbfBest ResponseYou've already chosen the best response.0
is it the line that goes down the middle?
 one year ago

kandsbbfBest ResponseYou've already chosen the best response.0
so how do i figure it out?
 one year ago

campbell_stBest ResponseYou've already chosen the best response.1
ok... so find half the distance spanned by the arch... then substitute that value into the equation for the bridge... that will give the height does that make sense..
 one year ago

kandsbbfBest ResponseYou've already chosen the best response.0
soooo divide 1777.07 by 2?
 one year ago

campbell_stBest ResponseYou've already chosen the best response.1
yep... then substitute it... the highest point is at the centre of the acrch
 one year ago

campbell_stBest ResponseYou've already chosen the best response.1
the original equation 0.000471x^2 + 0.837x
 one year ago

kandsbbfBest ResponseYou've already chosen the best response.0
okay so when i divided it by 2 i got 888.535..... which number do i sub that for in the equation?
 one year ago

kandsbbfBest ResponseYou've already chosen the best response.0
so do i sub that in for x?
 one year ago

campbell_stBest ResponseYou've already chosen the best response.1
yes so its \[0.000471\times(888.535)^2 + 0.837\times888.535\]
 one year ago

campbell_stBest ResponseYou've already chosen the best response.1
what did you get for the height..? the length is 1777.07
 one year ago

campbell_stBest ResponseYou've already chosen the best response.1
ok... which answer has height 371.85 and length 1777.07
 one year ago

campbell_stBest ResponseYou've already chosen the best response.1
thats it.. well done
 one year ago

kandsbbfBest ResponseYou've already chosen the best response.0
did we answer the last part of the question? How high above the river is the bridge (the top of the arch)? How long is the section of bridge above the arch?
 one year ago

campbell_stBest ResponseYou've already chosen the best response.1
yes... you have all the answers you need height = 371.85 and length 1777.07
 one year ago
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