Question

Rearrange the formula A = πr2

for r.
Responses
A r = Aπ−−−√
B r = A√/π
C r = π√/A
D r = A/π−−√

Answer 1

To rearrange A = πr^2 for r, divide by π and then take the square root of both sides, resulting in r = √(A/π). The correct answer is B. r = √(A/π), and ensures proper use of significant figures.

Step-by-step explanation:

The student is asking to rearrange the formula for the area of a circle, A = πr^2, to solve for the radius (r). To isolate r, follow these steps:

1. Divide both sides of the equation by π so that you have A/π = r^2.
2. Take the square root of both sides to solve for r. This gives you r = √(A/π).

So the correct rearrangement of the formula to solve for r would be B. r = √(A/π).

It is also important to note significant figures in calculations involving pi (π). For example, if a radius is given as 1.2 m (two significant figures), and we calculate area using π, the area should also be reported with two significant figures, such as A=4.5 m² to reflect the precision of the measurement.