Graphical methods in solving problems - Practice assessment

Question

Photo: http://i.imgur.com/0FPyP8K.png?1 

How do you convert this in to a graph?

I can use either functions: 

- Parabola 

- Cubic 

- Trigonometric graphs(Preferred)

- Square root  

- others

Answer 1

May I ask which class is this problem for?  It is really too vague and open-ended to be solved definitely. Just looking at the picture (thanks for no viruses!), it could be a parabola or inverted catenary (hyperbolic cosine curve), but it is probably just a parabola, as this is a common shape for suspension bridges. You could also fit it to a sine or cosine, and since that is indicated as preferred, you should try this first.

 

Here is a little help.

 

The length is 1200 m, so this is one-half of the sine period. The period would then be twice this, or 2400.

 

If the height above water is the distance from the water to the top of each arch, then you might take this as the amplitude of the sine function. The distance from the water to the roadway is clearly not a constant, and I am not sure what is expected of you here. Perhaps you need a second equation to describe the shape of the road as it travels through the three arches, but again this is not clear.

 

Good luck with this. The person who posed it is obviously out to waste your time or make you think about it when you would rather be doing something else. Fortunately, I like doing things like this on a Sunday, but it is up to you whether or not you want to proceed. I would try describing each arch as one-half of a sine wave, then go back to your instructor and ask for clarification.

 

Have a nice day!