Recent content by ratios

I learned that vertifcal tangents occur at a parametric curve if the derivative of the curve is undefined. That is given dy/dx = dy/dt / dx/dt, a vertical tangent occurs when dx/dt = 0. I don't understand why this is so. I know that vertical tangents occur when the slope is infinite, but...

Okay I see. Thanks for the help!

Hello all, I don't understand why |h|/h will become -1 as h approches 0 from the left. I can see how the numerator becomes negative, as |x| = -x if x< 0, but shouldn't the denominator become negative also since h < 0 when we approach 0 from the left? So why isn't the answer -h/-h = 1?