a) Sin C=8/17
sin C=AB/BC
8/17=16/BC =>BC =34 cm
In ∆ ABC dr =>TP
AB²+AC²=BC²
16²+AC²=34²
AC²=1156-256
AC=√900
AC=30 cm
P ABCD = AB+AC+BC =16+30+34=80cm
b)
Tg B=AC/AB
5/12=20/AB=>AB= 48 In ∆ABC dr =>TP
AB²+AC²=BC²
48²+20²=BC²
BC²= 2304+400
BC=√2704
BC=52 cn
P ABC=AB+AC+BC=48+20+52=120 cm
c)
cos C= AC/BC
3 /5=AC/15=>AC=9 cm
In ∆ ABC dr =>TP
AB² +AC² =BC²
AB² +9²=15²
AB² =225-81
AB=√144
AB=12 cm
P ABC =AB+AC+BC=12+9+15= 36 cm
d)
ctg B =AB/AC
3/4=18/AC=>AC=24
In ∆ ABC dr =>TP
AB² +AC² =BC²
18²+24²=BC²
BC²=576+324
BC=√900
BC=30 cm
P ABC = AB+AC+BC= 18+24+30=72 cm