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September 26

Body Roundness Index formula

364.2 − 365.5  × √(1 − [waist circumference in cm / 2π]²  /  [0.5 × height in cm]²)

which seems unnecessarily complicated. Why isn't it simply simplified to

364.2-365.5{\sqrt {1-{\Big (}{\frac {\text{waist circumference in cm}}{\;\;\;\;\pi \;\;\;\;\;\times \;\;\;\;\;\,{\text{height in cm}}}}{\Big )}^{2}}}

?

Moreover, as both numerator and denominator have length units, the unit doesn't matter as long as they are the same e.g. cm, mm or inches.

Probaly because the editor who added that didn't know how to render mathematical formulae. You're welcome to change it. Shantavira|^{feed me} 09:16, 26 September 2024 (UTC)[reply]

Thanks. I don't mean the formatting but the division by 2π on top with multiplication by 0.5 below.

Presumably, they meant waist / (2π) instead of (waist / 2)π – BEMDAS is confusing! cmɢʟee⎆τaʟκ 10:17, 26 September 2024 (UTC)[reply]

Because it's left over from its derivation from the eccentricity formula for an ellipse,

{\sqrt {1-{\frac {b^{2}}{a^{2}}}}}

, where the semi-minor axis, b, is the "radius" of the waist and the semi-major axis, a, is half the body height. AlmostReadytoFly (talk) 11:05, 26 September 2024 (UTC)[reply]