hi, I seem to have forgotten some math. I forgot how to rotate a graph about its axis. like say, if I had an elliptic paraboloid(z/c=(x^2)/a+(y^2)/b) how would I go about rotating those 90 degrees? like say I had the widest part along the x-axis and wanted to rotate it so it was along the y-axis.(without simply switching a and b)

To rotate the graph clockwise through t degrees around the z axis, make the following replacements in the equation:

Replace x with (x cos t - y sin t)
Replace y with (x sin t + y cos t)

So, to rotate by 90 degrees:

Replace x with -y
Replace y with x