Perpendicular Distance b/w point and line

Guiding questions for students

1.) How do we work out the co-ordinates of A given the co-ordinates of P are (x1,y1) 2.) Given your answer to Q1, how can we work out the length of AP? 3.) Check the box show gradient triangle, and then click show angles. What can we say about triangle ABC and triangle AQP? 4.) Given your answer to Q3, derive the length of PQ