Question

Find the DIAMETER of a circle for the circumference given.

circumference = 81 km
A) 4 km B) 10 km
C) 12 km D) 8 km

Answer 1

25.796... km

Explanation:

We are given that:

• Circumference: 81 km

Formula of circumference:

• 2πr or πd

Thus, we can rewrite the circumference as:

• 2πr = πd = 81 km

Since we are asked to determine the diameter, it is recommended to use the formula (πd). Therefore,

• πd = 81 km

Divide π both sides to isolate the diameter:

• ⇒ πd/π = 81 km/π
• ⇒ d = 81 km/π

Substitute π as 3.14 and simplify:

• ⇒ d = 81 km/3.14
• ⇒ d = 25.796... km

Therefore, the diameter of the circle is 25.796... km.