# Theorem of three perpendiculars - Lesson

- Author:
- Simona Riva

- Topic:
- Geometry

Let .
Draw the line in , through the plane is perpendicular to line

*P*be a point on a plane*r*, perpendicular to plane*P*, then a new line*t*in the same plane. Now draw the line*s*, perpendicular to*t*through*P*. Draw the plane*r*and*s*.*t*. Move the points in the construction and explore the theorem.