SOLUTION: Solve each formula for the indicated letter. Assume that all variables represent nonnegative numbers. A = pi*r^2 + pi*rs, for r (Surface area of a cone)

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: Solve each formula for the indicated letter. Assume that all variables represent nonnegative numbers. A = pi*r^2 + pi*rs, for r (Surface area of a cone)       Log On


   

Question 464008: Solve each formula for the indicated letter. Assume that all variables represent nonnegative numbers.
A = pi*r^2 + pi*rs, for r (Surface area of a cone)
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Solve each formula for the indicated letter. Assume that all variables represent nonnegative numbers.
A = pi*r^2 + pi*rs, for r (Surface area of a cone)
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Rearrange:
pi*r^2 + pi*rs - A = 0
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Divide thru by "pi":
r^2 + sr - A/pi = 0
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Quadratic Formula:
r = [-s +- sqrt[s^2 - 4*1*(-A/pi)]/2
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r = [-s +- sqrt[s^2 +[4A/pi]]]/2
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Cheers,
Stan H.
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