E2.4 Construct circles when given the radius, diameter, or circumference.
Activity 1: Drawing Circles
- Draw two circles:
- a circle with a radius of 5.2 cm;
- a circle with a diameter of 12 cm.
- A paper measures 20 cm by 24 cm. Draw the largest circle that would fit on the paper. What is its radius?
- A drill bit has a diameter of 1 cm. Is this enough to make a hole with a 4 cm circumference? Construct a circle to check your answer.
- Draw a circle with a radius of 8 cm and another circle with a diameter of 8 cm. Explain the differences between them.
Source: translated from En avant, les maths!, 7e année, ML, Sens de l’espace, p. 16-18.
Activity 2: Problems Related to the Construction of Circles
- Draw a donut with an inner radius of 2 cm and an outer radius of 4 cm.
- Draw three circles, the first with a radius of 8 cm, the second with a diameter of 12 cm and the third with a circumference of 40 cm. Describe your strategies for constructing them.
- Can a propeller of 20 cm diameter rotate in a straight cylinder of 65 cm diameter without touching the wall?