Golden Gate Bridge word problem

[mdd]

The Golden Gate Bridge is supported by two huge cables strung betwen the towers at each end of the bridge. The function f(x)= .0001193x - .50106x + 526.113 gives the approximate height of the cables above the roadway at a point on the road x feet from one of the towers. The cables touch the road halfway between the two towers. How far apart are the towers?

I calculated the vertex (x = -b/2a) as being 130. But, I do not know what to do with it now. Can someone provide some direction?

MDD

 

[tkhunny]

1) You had better calculate that vertex again. 130 what? Keep some units around. You'll be much happier.

2) Is it likely that the vertex is the middle, where the cables touch the road?

 

[skeeter]

twice the vertex distance from the origin = length between the towers

recalculate the x-position of the vertex ... you are way off.