Two circles have a common center, the radius of one 8cm, its length is 4/5

| July 25, 2021 | education

Two circles have a common center, the radius of one 8cm, its length is 4/5 of the diameter of the second circle, find the radius of the second circle.

According to the condition of the problem, the radius of the first circle is 8cm, while 8cm is equal to 4/5 of the diameter of the second circle.
Before finding the radius of the second circle, let’s calculate what its diameter is.
1.) 8: 4 = 2 (cm) – 1/4 of the diameter of the second circle.
2.) 2 × 5 = 10 (cm) – the diameter of the second circle.
Otherwise, these two actions can be written in another way:
8: 4/5 = 8 × 5/4 = 40: 4 = 10 (cm) – the diameter of the second circle.
Since the radius is half the diameter, we consider:
3.) 10: 2 = 5 (cm) – the radius of the second circle.
Answer: 5cm.



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