Math Problem...is this correct?

[dauerbach]

A circle has an area of M sq.cm. and a circumference of N cm. If M/N = 20, what
is the radius of the circle in cm?

I end up with pi * r * r/ pi * 2 * r.

Simplifying, I get r/2 = 20, r = 40 cm.

[panache45]

Right.

[CookingWithGas]

I agree

FWIW

BTW for the sake of anal retention I would have written (pi * r * r)/ (pi * 2 * r).

[Santo_Rugger]

That’s not anal retention, that’s just the proper way to write it. If you inserted the problem as written into MatLab or a calculator as written, you wouldn’t get the right answer.

[tim314]

@CookingWithGas

BTW for the sake of anal retention I would have written (pi * r * r)/ (pi * 2 * r).

And for the extra retentive:
(π r[sup]2[/sup]) / (2 π r)

[Snarky_Kong]

@Santo_Rugger

That’s not anal retention, that’s just the proper way to write it. If you inserted the problem as written into MatLab or a calculator as written, you wouldn’t get the right answer.

Then only the second set of parenthesis would be necessary.

[DrCube]

@Snarky_Kong

Then only the second set of parenthesis would be necessary.

Better yet, instead of parentheses, replace the last two *'s with /'s. You’ll get the right result with a minimal amount of symbols.

[Santo_Rugger]

@Snarky_Kong

Then only the second set of parenthesis would be necessary.

Depends on your definition of necessary. While MatLab doesn’t need them, I sure do. A recent line of MatLab code in a program I wrote was this:

P(t) = (P(t-1)^((1-k)/(2k)) + (t - (t-1)) * (CA/V) * ((k-1)/(2k)) * ((gc * R * k^3 /M) * (T(1)/(P(1)^((k-1)/k))) * (2/(k+1))^((k+1)/(k-1)))^(1/2))^(1/((1-k)/(2k)));

You might disagree, but I say that all the parenthesis are necessary.