Anonymous asked in Science & MathematicsMathematics · 1 decade ago

Make R subject of formula: please?

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

how do i make R the subject

4 Answers

  • 1 decade ago
    Favorite 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.


  • 1 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.

  • norman
    Lv 7
    1 decade ago

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

    A/pi + r^2 = R^2

    R = sqrt(A/pi + r^2)

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