You can plug both equations in desmos, set a slider for c, and move till it intersects one point. You can also use the discriminant b^2 - 4ac. If the line intersects the parabola at only one point, then the discriminant must be equal to 0. In Desmos, you set the two equations equal to each other to rewrite everything in the standard quadratic form, and then you can use a regression to solve for c.

@Scott Robinson thanks, you're the goat

@Scott Robinson thanks

@Scott Robinson thanks bro