Topic 3 Presentation of Educational Material

[Material: Second Class of Gymnasium (B3.5)]

Duration: 5-10’

Analysis of Mathematical Type: Circle Area (circular disc) e = π r2

A circular disc is part of the plane enclosed by a circle.

To calculate the area of a circular disc, divide the circular disc into as smaller as we can. Cut these pieces and then place them as shown in the figure:

We observe a rectangular-like shape, whose “base” is equal to the length of the circle, that is, the π × r, and the “height” with the ray of the circle. Therefore the area of the circular disc is equal to the area of the rectangle formed, that is, with r × π r

The area of the circular disc of radius r equals E = πr2