c) sin C = AB/BC
AB/24 = 5/6
AB = 120/6 = 20 cm
[tex]AC=\sqrt{BC^2-AB^2}=\sqrt{24^2-20^2}=\sqrt{576-400}=\sqrt{176}=4\sqrt{11}[/tex]
[tex]ctgB=\frac{AB}{AC}=\frac{20}{4\sqrt{11}}=\frac{5}{\sqrt{11}}[/tex]
d) tg B = AC/AB
AC/4 = 2,5
AC = 10 cm
[tex]BC=\sqrt{AB^2+AC^2}=\sqrt{4^2+10^2}=\sqrt{16+100}=\sqrt{116}=2\sqrt{29}[/tex]
[tex]sinB=\frac{AC}{BC}=\frac{10}{2\sqrt{29}}=\frac{5}{\sqrt{29}}[/tex]
[tex]cosB=\frac{AB}{BC}=\frac{4}{2\sqrt{29}}=\frac{2}{\sqrt{29}}[/tex]
