Question

Juan wants to know the cross-sectional area of a circular pipe. He measures the diameter which he finds, to the nearest millimeter, to be 5 centimeters.

To find the area of the circle, Juan uses the formula A=2〖πr〗^2 where A is the area of the circle and r is its radius. He uses 3.14 for π. What value does Juan get for the area of the circle? Make sure you include your units.

Michelle found the area of a circle as 78.5 〖in〗^2. She used 3.14 for π. What is the radius of the circle? Explain how you found your answer.

(Help please)

Answer 1

Explanation:

Juan wants to know the cross-sectional area of a circular pipe. He measures the diameter which he finds, to the nearest millimetre, to be 5 centimetres

It means radius is 2.5 cm. For the area of circle he gets the formula as :

`A=\pi r^2\\\\A=3.14* (2.5)^2\\\\A=19.62\ cm^2`

If Michelle found the area of a circle as
`A=78.5\ in^2`

So,

`A=\pi r^2\\\\r=\sqrt{(A)/(\pi)} \\\\r=\sqrt{(78.5)/(3.14)} \\\\r=5\ \text{inch}`