Question

What Is the radius of a circle when the area is 15.9 in

Answer 1

Work backwards! First, what's the formula for the area of a circle?

Answer 2

\(\ \Huge \text{?} \) @Rmacpherson

Answer 3

\(\ \Huge \text{Well, I'll get you started:} \)

Answer 4

\(\ \Large \text{The area of a circle is } A=\pi r^2,\)
\(\ \Huge \text{Right?} \)
\(\ \Large \text{So, given 15.9 sq in is the area of the circle or A }\)
\(\ \Large 15.9=\pi r^2 \)
\(\ \Large \text{How could we solve for r (the radius) now?} \)

Answer 5

\(\ \Huge \text{So close! Try again!!} \)

Answer 6

\(\ \Large \text{Do you see where you went wrong?} \)

Answer 7

|dw:13891494958is it 8.98

Answer 8

because I
Didn't

Answer 9

square root pi

Answer 10

Not square root pi, but you're right about forgetting to square root! What did you forget to square root?

Answer 11

so it's not 8.98

Answer 12

Nope!

Answer 13

nut the area is 15.90 squared so i would just divide 15.90 by pi right?

Answer 14

Let's go back to the equation!
So, to solve for r, we get

\(\ \Huge \frac{15.9}{\pi}=r^2...\text{That's } r^2 \text{ though!} \)
\(\ \Huge \text{How would we solve for } r??? \)

Answer 15

\(\ \Huge \text{Remember: } \)
\(\ \Large \text{The radius of a circle isn't } inches^2, \text{ it's only } inches! \)

Answer 16

then I would square root 15.9 and pi right or just 15.9 and why

Answer 17

Square root 15.9 and pi because remember? The radius is not in square inches, it's only in inches, so by square rooting, we get inches alone! What's the final answer you get?

Answer 18

I got 2.25

Answer 19

Quick recap here:
So we have the formula \(A=\pi r^2\).
We plugged in A=15.9, so we got \(15.9=\pi r^2\).
Then we did put the \(\pi\) to the left hand side: \(\dfrac{15.9}\pi=r^2\).
Then you're now asked to solve for \(r\).

Answer 20

so is it 2.25 inches

Answer 21

Why are you putting a blank drawing every time lol

Answer 22

Yes

Answer 23

it won't let me reply any other wag srry but thank you

Answer 24

no problem :)