SOLUTION: A=pir^2 for r and p=2(l+w) for w Please help me with the answers to these questions. Thank You.

Algebra ->  Expressions-with-variables -> SOLUTION: A=pir^2 for r and p=2(l+w) for w Please help me with the answers to these questions. Thank You.      Log On


   

Question 632865: A=pir^2 for r

and


p=2(l+w) for w

Please help me with the answers to these questions. Thank You.
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
The equation to calculate the area (A) of a circle having the radius (r) is
A=pi%2Ar%5E2
Solving for r
A=pi%2Ar%5E2 --> A%2Fpi=pi%2Ar%5E2%2Fpi --> A%2Fpi=r%5E2
Assuming that r is not a negative number, the only solution is
highlight%28r=sqrt%28A%2Fpi%29%29
If A and r had other meanings, so that r could be negative, r=-sqrt%28A%2Fpi%29 would be another solution.
The equation to calculate the perimeter (P) for a rectangle with length L, and width W is
P=2%28L%2BW%29
Solving for w,
P=2%28L%2BW%29 --> P=2L%2B2W --> P-2L=2L%2B2W-2L --> P-2L=2W --> %28P-2L%29%2F2=2W%2F2 --> highlight%28W=%28P-2L%29%2F2%29
NOTE: I used capital L because lowercase l can be confused with the number one.