Altitudes and orthocenter of a triangle

An altitude of a triangle is a line segment that is drawn from the vertex to the opposite side and is perpendicular to the side. A triangle can have three altitudes. Point of intersection of these lines for different types of triangles is explored.

Objectives
Introduce altitudes of a triangle and their point of concurrence.

Estimated Time
30 minutes

Prerequisites/Instructions, prior preparations, if any
Types of triangles and concept of altitudes should have been covered.

Materials/ Resources needed
Digital resources: Laptop, geogebra file, projector and a pointer.

Geogebra resources: Concurrency of altitudes.ggb

Process (How to do the activity)

 * 1) Project the geogebra file and ask the following questions.
 * Developmental Questions:
 * 1) Which type of triangle is this ?
 * 2) What is an altitude ?
 * 3) How do we construct an altitude ?
 * 4) What is the point of concurrence of 3 altitudes called ?
 * 5) Identify the position of point of concurrence in different triangles.
 * Evaluation:
 * 1) What are the positions of orthocentre in different types of triangles.
 * Question Corner:
 * 1) Find the applications of orthocentre.