GR11 Math: finding endpoints of chord within a circle.

Given...

**1**. Point P is on the line and is 10 units from the origin. Determine the coordinates of P.

I've gotten this far...

So:

.

Then .

Plugging in y...

This is where I'm stuck since I cannot factor it. When the quadratic formula is applied, the number inside the brackets is a negative number.

2. Given...

From a lighthouse, the range of visibility on a clear day is 40km. On a coordinate system, where O(0,0) represents the lighthouse, a ship is travelling on a course represented by . Between which two points on the course can the ship be seen from the lighthouse?

I got this far...

Plugging it in...

Again, I am stuck with the same problem. I get a negative number when the quadratic formula is applied.

What am I doing wrong here? Thank you so much!

N.