This might be messy.

The fundamental equation:The equation of a line passing through with slope is .

Thus, find a point on this parabola ( ) such as it is a tangent and passes through because this is the point of the tower. I am going to use the fundamental equation for this problem which I stated in the previous paragraph. But to use it you need to know the slope at point and the y-coordinate of that point . But it slope is its derivative there thus it is. and

Thus, the equation of the tangent for any point is substitute your values to get watch the negative signs

Simplify,

Simplify further,

Now the line passes through thus when then substitute that infromation into the equation

Thus,

(which is true you can draw this tangent through two points one on the right and one on the left). But the picture is positioned on the right thus,

Substitute that into your tangent equation thus,

This answers part one.

Q.E.D.