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Anonymous

# Make R subject of formula: please?

A = pi(R + r)(R-r)

how do i make R the subject

### 4 Answers

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- 1 decade agoFavorite Answer
(R+r)(R-r) = A/pi

R²-r² = A/pi <--- this is the difference of two squares method

R² = A/pi + r²

R = √(A/pi+r²)

- 1 decade ago
Do you mean by putting R on the left side of the equation?

They'll be: R= {[A+pi*(r^2)]/pi}^(0.5).

It isn't complicated at all, just the typing makes it be.

Vive

- Randy PLv 71 decade ago
Multiply it out.

A = pi(R^2 - r^2) = pi*R^2 + pi*r^2

Now you can get the R^2 on one side and everything else on the other side and then take the square root.

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