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Fie un triunghi dreptunghic in A,ABC in care AD este inaltimea ,D apartine (BC) daca AB=4radical din 3 si BD=5 calculati aria si perimetrul

Răspuns :

in ΔABC dreptunghic A=90
tg C=AB/AC
tg 30=√3/3
√3/3=4√3/AC
AC=12√3/√3
AC=12
BC=√AB²+AC²
BC=8√3
AD=AB*AC/BC
AD=6
A=B*h/2
A=8√3*6/2
A=24√3
P=4√3+8√3+12
P=12√3+12
daca AD=inaltime
atunci apl T Pitag in Triung ADB(D=90)
AD²=AB²-DB²
AD²=(4√3)²-5²
AD²=48-25
AD=√23
din teor.inaltimii AD²=BD*DC
23=5*CD
CD=23/5
dar BC=CD+DB
BC=23/5+5
BC=48/5
Apl TP in ABC
AC²=BC²-AB²
AC²=(48/5)²-(4√3)²
AC²=1104/25
AC=(√1104)/5
P=4√3+48/5+√1104/5
A=(C1*C2)/2
A=(4√3*√1104/5)/2=2√3312/5=(2*57.54)/2⇒A=115.1/2⇒A=57.55cm²