Finding the area of a circle given the area?

A circle has a circumference of 10π cm. What is the area if this circle? Justify your answer completely.

✐Explanation✐

C = 2πr (circumference of a circle)
A = πr² (area of a circle)

Use the circumference formula to determine r first. Then, use the area formula to determine the answer.

C = 10π

10π = 2πr

r = 5 cm

Substitute that to the area formula…

A = π(5)²

Therefore…

A = 25π cm²

I hope this helps!

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One Response to “Finding the area of a circle given the area?”

θκѕθ єℓιτα™ 〓ɹǝɹǝʍsuɐ uɐıuoɔɐɹp on May 31st, 2010 at 4:44 am

✐Explanation✐

C = 2πr (circumference of a circle)
A = πr² (area of a circle)

Use the circumference formula to determine r first. Then, use the area formula to determine the answer.

C = 10π

10π = 2πr

r = 5 cm

Substitute that to the area formula…

A = π(5)²

Therefore…

A = 25π cm²

I hope this helps!
References :
Knowledge

Area List