Proof of the Theorem:
We need to prove that the tangent line p is perpendicular to the radius OH at the point of tangency H.
Given: Line p is tangent to circle with center O, H is the point of tangency.
To Prove: p ⊥ OH.
Proof:
- Let A be any point on the tangent line p, other than H.
- Since p is tangent to the circle at H, every other point A on p must lie outside the circle.
- Therefore, the distance OA must be greater than the radius R (which is equal to OH). So, OA > OH.
- This means that OH is the shortest distance from the center O to the line p.
- By definition, the shortest distance from a point to a line is the perpendicular distance.
- Hence, the line segment OH must be perpendicular to the tangent line p.
- Therefore, p ⊥ OH.
Theorem proved.