Question

Fie triunghiul ABC,m(∡A)=90° si AD⊥ BC,D∈BC.
a)Daca AD=6 cm si DC=9 cm,calculati BD
b)Daca AB=6 cm si AC=8 cm si BC=10 cm,calculati AD
c)Daca AD=0,5 m si BC= 20 dm,calculati AB·AC
d)Daca BC=35 cm si CD= 4BD,calculati BD,DC,AD

Answer 1

[tex]a) AD^{2} = DC X BD \\ 36=9 X BD , BD= 4 \\ b( AD= \frac{AB X AC}{BC} = \frac{6 X 8}{10} = \frac{24}{5} \\ [/tex]
c) formula pct b) inlocuieste niole valori si calculeaza
d) DC=4BD ; BC=BD+DC=BD+4BD=5BD ;  35=5BD deci BD= 35/5=7
DC=4 X 5=20  ;[tex] AD^{2} =BD X BC = 7 X 20 =140 \\ AD= \sqrt{140} =2 \sqrt{35} [/tex]