1 BC²=AB²+AC²=72+36, BC=6√3
sinB=AC/BC=6/6√3=1/√3=√3/3
cosB=AB/BC=6√2/6√3=√2/√3=√6/3
tgC=AB/AC=6√2/6=√2
2. a. P=2(L+l)=68, L+l=34
L/12=l/5=(L+l)/(12+5)=34/17=2
L=12x2=24 cm
l=5x2=10 cm
b. A=Lxl=240 cm²
3. a.ABCD trapez dreptunghic, AD inaltime
A=(AB+CD)xAD/2=(13+9)x3/2=33 cm²
b. P=AB+CD+AD+BC
BM⊥CD, BN II AD, BM≡AD=3, CD=DM+MC, MC=CD-DM=13-9=4
BMC triunghi dreptunghic, BC²=BM²+MC, BC=5 cm
P=9+13+3+5=30 cm
c. ADC triunghi dreptunghic , t lui Pitagora
AC²=AD²+DC²=9+169=178, AC=√178
ABD triunghi dreptunghic, t lui Pitagora
BD²=AD²+AB²=9+81=90, BD=3√10
