E2.4 Construct circles when given the radius, diameter, or circumference.
Skill: Constructing Circles
Example of the Construction of a Circle with a Radius of 5 cm
In order to draw a circle, we must first determine the measure of its radius. Then, open the compass and use a ruler to measure the opening of the compass so that it matches the radius measurement. Draw the outline of the circle with the pencil, making sure to keep the point of the compass in the center of the circle.
Example of the Construction of a Circle with a Radius of 5 cm
Source: adapted and translated from En avant, les maths!, 7e année, CM, Sens de l’espace, p. 5.
Compasses are often used to construct circles by hand. Another strategy is to attach a pencil to the end of a string. The radius must be known when using a compass or string to construct a circle.
Circles of given measurements can also be constructed using technology. Dynamic geometry applications show how changes to the radius, the diameter, or the circumference affect the others.
Source: The Ontario Curriculum. Mathematics, Grades 1-8 Ontario Ministry of Education, 2020.