Circle Geometry

This resource consists of four interactive excel files dealing with the circumference and area of circles and some of the main circle theorems.

Circle: Circumference
This file begins with a sheet which allows measurements of circumference and diameters to be plotted and the line of best fit is automatically drawn. The formula C=πD is stated and sets of questions give practice at finding circumference, diameter and radius. The next sheets deal with the perimeter of semi-circles and 3/4 circles. Further sheets of questions are provided for use within the classroom.

Circle: Sectors, Area
Like the previous activity this file begins with a practical. Students estimate the areas of circles and are able to enter these values into tables of values for the area against radius and radius2. A line or curve of best fit is automatically drawn on the two graphs then the formula A=πr² is stated. The next sheets deal with areas of sectors and sets of questions requiring use of the formula A=πr². Further sheets of questions are provided for use within the classroom.

Circle Geometry: Angle at Centre and Circumference
This activity illustrates the fact that the angle at the centre is twice the angle subtended at the circumference. There are three main interactive sheets where angles can be hidden or shown so that understanding can be checked and developed. There are further sheets with questions on related topics including bearings, similarity and the Cosine Rule.

Circle Geometry: Angles in the Same Segment
This excel file begins with defining the terms used and then two angles in the major segment are shown. Subsequent interactive sheets allow many more such angles to be shown, both in the major and minor segments. Students can reveal answers to the size of angles and in doing so test their understanding. One sheet deals with the angles in some cyclic quadrilaterals. This excel file concludes with the same further sheets of questions as the previous file.

Note
This program was designed by be viewed on a screen with a resolution of 1024 x 768. Users may have to adjust the resolution of their screen for the pages to display as was originally intended. The program uses macros which need to be enabled on users’ machine.