Răspuns:
Explicație pas cu pas:
a) AC²=BC²-AB²=(20+13)(20-13)=33×7=231
AC=15,19
sin C=AB/BC=13/20
cosC=AC/BC=15,19/20
tgB=AC/AB=15,19/13
ctgB=AB/AC=13/15,19
b) BC²=AB²+AC²=6²+3×6²=3×6² BC=6√4=12
sinB=AC/BC=6√3/12=√3/2 B=60°
cosB=AB/BC=6/12=1/2
tgB=AC/AB=6√3/6=√3
ctgB=1/√3=√3/3
c)cosB=1/2 B=60°
cosB=AB/BC 1/2=12/BC BC=24
AC²=BC²-AB²=24²-6²=(24-6)(24+6)=18×30 AC=6√15
sinB=√3/2
sinC=1/2 cosC=√3/2 tgB=√3 ctgB=√3/3
tgC=√3/3 ctgC=√3
d) tgC=AB/AC =1,25 AB/24=1.25 AB=24×1,25=30
BC²=AC²+AB=24²+30=1476 BC=38,41
sinB=AC/BC=24/38,41=0,62
cosB=AB/BC=30/38,41=0,78