在Rt△ABC中,∠C=90° BC:AC=3:4, 则BC:AC:AB==3:4:5=k.
即,BC=3k, AC=4k,AB=5k.
sinA=BC/AB=3k/5k=3/5;
cosA=AC/AB=4k/5k=4/5.;
tanA-BC/AC=3k/4k=3/4;
cotA=AC/BC=4/3.
在Rt△ABC中,∠C=90° BC:AC=3:4, 则BC:AC:AB==3:4:5=k.
即,BC=3k, AC=4k,AB=5k.
sinA=BC/AB=3k/5k=3/5;
cosA=AC/AB=4k/5k=4/5.;
tanA-BC/AC=3k/4k=3/4;
cotA=AC/BC=4/3.