Math HW!!! don't get at all!!?

Question

k....The area of a circle is 2.0096 square inches. Use 3.14 as an approximation for the number [pi]

what is the diameter of this circle??

what is the cirsumference of this circle??

oh yeah if you answer can you show me how to do it! cause i wanna learn!!

thanx sooo much one quick review....

so the diameter is 0.16....cause (.8)(.8)=(.64)(3.14)=2.0096
basically r times r times *pi*=area
and d=r^2 so 0.8+0.8=0.16

the circumference is...0.5024....cause (0.16)(3.14)=0.5024

am i right??

Answer 1

The formula for the area of a circle is: A=πr^2
In the formula A is equal to the area, Pi as stated above equals 3.14 and r^2 is the radius squared.
The diameter of the circle is equal to 2r.
By formula you have
A = 2.0096
Pi = 3.14
r = unkown
2.0096 = (3.14)(r^2)
divide both sides by 3.14
(2.0096)/(3.14) = r^2
if you are using a calculator you can solve for r form this point.
The diameter is 2r
The circumfernce of a circle is C=πd
Where C is circumference, d is diameter.
Use the r value from the area formula above and substitue 2r for d.

Answer 2

The formula for the area of a circle is:
(pi) * R^2 = A

Since we know the area of the circle (2.0096) and the value being used for Pi (3.14), we plug the numbers in and solve it algebraically.

(3.14) * R^2 = 2.0096

R^2 = (2.0096)/(3.14)

R^2 = 0.5910588 (and some--it's a nonrepeating decimal; try it on your caluculator and you'll see what I mean.)

Take the square root of both sides, now:
R = 0.7688

This is the radius of the circle.

But we didn't want the radius, did we? We want the diameter and the circumference! What do we do?

Well, since the diameter is twice the radius:

R * 2 = D

D = 1.5376 inches.

So that's got that handled. But what about the circumference? That's the length all the way around the circle.

The formula for that is:
2 * (pi) * R

Well, now--that's easy! We have all these numbers already!

2 * (3.14) * (0.7688) = 4.828 inches.

See how that works?

Answer 3

Area is pi r^2 where r is the radius.
So r^2 = 2.0096/3.14.
so r = sqrt(2.0096/3.14)
so d = diameter = 2 * sqrt(2.0096/3.14)

When you've put this in your calculator, you know r, so the circumference is just 2 * pi * r. (or just pi * d if you prefer)
.

Answer 4

π is the ratio of the circumference of a circle to its diameter so

π D = C

The area of a circle is

2π ( 1/2 D )^2

You know the area; use that last equation to solve for the diameter D. Then use the first equation to solve for the circumference C.

Answer 5

area of a circle of diamter d is

A = Pi (d^2) /4 = 3.14 d^2 /4 = 2.0096

d^2 = 4(2.0096)/(3.14) =2.56

d = sqrt(2.56) = 1.6 in

Circumference = Pi d =
3.14 d = 3.14 * 1.6 = 5.024 in

Answer 6

A = πr^2
r = d/2
A = π(d/2)^2 = (1/4)πd^2
d^2 = 4A/π
d = √(4A/π) = 2√(A/π)
d ≈ 2√(2.0096/3.14)
d ≈ 1.6 in.

C ≈ 3.14(1.6 in.) ≈ 5.024 in.