Răspuns:
Explicație pas cu pas:
T Pitagora
AB²=BC²-AB²=100-75=25 AB=5 cm AC=5√3 cm BC=10 cm
sin B=AC/CB=5√3/10 =√3/2 ⇒∡B=60°
sin C=AB/BC=5/10=1/2 ⇒∡C=30°
cosB=1/2
cos C=√3/2
tg B=√3 ctg B=√3/3
tg C=√3/3 ctg C=√3
2.
tgB=AC/AB=√3/3 ∡B=30° ⇒∡C=60°
ctg B=√3 ctgC=√3/3
ctg B+ctgC=√3+√3/3=√3(1+1/3)=4√3/3