make r the subject of the formula
a=4PIErsquared
thanks :)
MATHS algebra!!!!!!!!!!?
2009-03-24 11:43 am
回答 (7)
2009-03-24 11:57 am
✔ 最佳答案
A=4πr^2r^2=A/4π
r=√(A/4π)
r=1/2√(A/π) answer//
2009-03-24 11:48 am
a=4PIErsquared
squareroot(a/(4pie)) = r
squareroot(a/(4pie)) = r
2009-03-24 11:48 am
A = 4 pi r^2
so r^2 = A/4pi
or r = sqrt(A/4pi)
so r^2 = A/4pi
or r = sqrt(A/4pi)
2009-03-24 11:59 am
a = 4πr^2
4πr^2 = a
r^2 = a/(4π)
r = √[a/(4π)]
4πr^2 = a
r^2 = a/(4π)
r = √[a/(4π)]
2009-03-24 11:57 am
"Make r the subject of the formula" mean you need to rearrange the equation so it starts out "r = ...."
The rule: Always apply operations to both sides of the equation.
a = 4πr²
Divide both sides of the equation by 4π
a/(4π) = r²
Take the square root of both sides of the equation
±√(a/(4π)) = r
Clean it up
r = ±½√(a/π)
http://www.flickr.com/photos/dwread/3382137344/
-----
Note:
π is spelled "pi"
"pie" is http://farm1.static.flickr.com/1/861969_b80c870934.jpg?v=0
The rule: Always apply operations to both sides of the equation.
a = 4πr²
Divide both sides of the equation by 4π
a/(4π) = r²
Take the square root of both sides of the equation
±√(a/(4π)) = r
Clean it up
r = ±½√(a/π)
http://www.flickr.com/photos/dwread/3382137344/
-----
Note:
π is spelled "pi"
"pie" is http://farm1.static.flickr.com/1/861969_b80c870934.jpg?v=0
2009-03-24 11:51 am
Divide by 4pi:
a/(4pi) = r^2
Take the square root:
r = +/-sqrt((a/4pi))
a/(4pi) = r^2
Take the square root:
r = +/-sqrt((a/4pi))
2009-03-24 11:50 am
ok the 1st thing you do is put it all under 1 Square root sign..cant make them on keyboards but can try!.... /------ kinda like that if you get it?:P
v
next is to dive the whole lot by 4pie...so put a big *** line under the equation and then write 4pie underneath...and then your left with R!
so its the square-root of A
------------- = R!...who's the daddy!! :-P
4 pie
v
next is to dive the whole lot by 4pie...so put a big *** line under the equation and then write 4pie underneath...and then your left with R!
so its the square-root of A
------------- = R!...who's the daddy!! :-P
4 pie
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