Question

Va rog frumos 42,44,47.

Answer 1

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Answer 2

42)
BC=8 cm, EC=6,4 cm
BE⊥AC
teorema catetei BC in tr. ABC
BC^2=EC x AC
64=6,4 x AC
AC=10 cm
pitagora in ABC, AB=6 cm
aria ABCD=BC x AB=48 cm2
44)
in dreptunghi diagonalele sunt congruente si se injumatatesc
sin (AOD)=0,6
AC=10 cm, AO=DO=AC/2=5 cm
aria AOD cu sinus
A=AO^2 sin (AOD)/2=25 x 0,6/2=15/2 cm2
aria ABCD=4 x A=30 cm2
47)
OE⊥AB
d(O;AB)=OE=4 cm
∡OAB=90-75=15°
teorema unghiului de 15° ⇒ OE=AB/4
AB=16 cm
perimetrul ABCD, P=4 x AB=64 cm
aria AOB, A=AB x OE/2=16x4/2=32 cm2
aria ABCD=4xA=128 cm2