Measuring the diameter of a circle using a ruler requires the knowledge of what the diameter of a circle is.
The diameter of a circle is simply the radius of the circle multiplied by 2. In other words, one can simply measure the radius of a circle and multiply it by 2 in order to get the diameter of the circle.
The radius of a circle in itself is the distance between the center of the circle and to any endpoint of the circle.
Hence, in order to measure the diameter of the circles in question, just measure the radius of each circle using a ruler, multiply it by 2 and record your measurements.
If you had used the cm reading on the ruler to record your measurements, each diameter in cm can be converted to mm as follows:
1 cm = 10 mm
Assuming that a particular diameter reads 10 cm:
10 cm = 10 x 10 mm
= 100 mm.
In other words, just multiply your measurement by 10 in order to convert them to mm.
More on measurement and conversion can be found here: https://brainly.com/question/13710038
