比ひ例れい式しき

noun

proportional expression; proportion equation

A mathematical expression showing that two ratios are equal, such as a:b = c:d.

• 比ひ例れい式しき a:b = c:d で、aとdを外そと項こう、bとcを内ない項こうという。

  In the proportional expression a:b = c:d, a and d are called the extremes, and b and c are called the means.