# Points of tangency

1. Nov 17, 2004

### ziddy83

I have the following function given, and I need to find the points of tangency...
Two tangent lines to the huperbola $$9x^2 - y^2 =36$$ interesect at the y-axis.

Use implicit differentiation to find the points of tangency.

Ok so i multiplied both sides by dy/dx, and solved for y'...i got
$$y'= \frac {9x}{y}$$
so to find the points of tangency, do i plug in the x and y values? im a little confused on that...thanks.

2. Nov 17, 2004

### ziddy83

Can anyone help?

3. Nov 17, 2004

### ziddy83

anyone at all???