AB=6 cm
AC=8 cm
BC=√(8²+6²)=√(64+36)=√100=10 cm
a) sinC =AB/BC = 6/10=2/5
cos C=AC/BC=8/10=4/5
tg C =AB/AC = 6/8=3/4
ctg C=AC/AB=8/6=4/3
b) sin B =AC/BC=8/10=4/5
cos B =AB/BC = 6/10=3/5
tg B =AC/AB=8/6=4/3
ctg B =AB/AC = 6/8=3/4
c) sin² B+2 sin C cos C= (4/5) ² +2 × 3/5 ×4/5 =16/25+24/25=40/25=8/5
d)tg² C - tg B ctg B= (3/4)² - 1= 9/16-1=-7/16
tg B ctg B= tgB × 1/tg B =1
