Acable hangs between two poles of equal height and 30 feet apart. set up a coordinate system where the poles are placed at x=−15 and x=15, where x is measured in feet. the height (in feet) of the cable at position x i

A cable hangs between two poles of equal height and 30 feet apart. Set up a coordinate system where the poles are placed at x=−15 and x=15, where x is measured in feet. The height (in feet) of the cable at position x is 

h(x)=14cosh(x/14)

cosh(x)=(e^x+e^−x)/2 i

I don't know how to explain this, I'm really bad at it!