Natural draft cooling towers are shaped like hyperbolas for more efficient cooling of power plants. The hyperbola in the tower at the right can be modeled with the equation x^2/16-y^2=225=1 with the units in meters. Find the width of the tower at the top and at its narrowest point in the middle.

The picture shows a tower that is 150 m tall and the sides of the tower form a hyperbola opening to the left and right.

I know we can make the center (0,0) and the vertices would be (4,0) and (-4,0). I am confused though because the covertices would be (0,-15) and (0,15). This would give a height of 30m, but the diagram shows a height of 150 m.

It is on p. 653, #32 here:

http://www.glencoe.com/sites/common_...H10_895267.pdf