Line Tangent to a Sphere

Line Tangent to a Sphere

For line:

$$\vec r=\vec a+\lambda\vec d$$

and sphere with centre $$\vec c$$ and radius $$r$$, tangency requires:

$$\frac{|(\vec c-\vec a)\times\vec d|}{|\vec d|}=r$$

Usage

- Used when a line is given in vector form and its tangency to a sphere must be checked.