Since A' < 90° (in fact, A is an angle of a triangle and thus < 180°; hence,), we have cot A' > 0; therefore, we can conclude . Analogously, and .
Since A '<90 ° (sa katunayan, ay isang anggulo ng isang tatsulok at sa gayon ay <180 °; kaya,), Kami ay higaan A '> 0, kaya naming tapusin . Analogously, at .