Question

Calculati aria unu romb cu perimetrul de 68 cm si una din diagonalele de 16 cm
Urgeeent!!!!!!!!!

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Answer 1

P=4l

68=4l

4l=68/÷4

l=17 cm

d=16 cm

Fie O mijlocul lui [AC]=> AO=OC=AC/2=16/2=8(cm)

In tr. COB.

m(<O)=90°=> OB²=BC²-OC²

OB²=17²-8²

OB²=289-64

OB²=225

OB=

$\sqrt{225}$

OB=15 cm=>BD=2OB

BD=2×15

BD=30 cm

A=d1×d2/2

A=16×30/2

A=480/2

A=240 cm²

Answer 2

P = 4AB => AB = 68/4 = 17 cm

In ΔABD duc AE ⊥ BD

AE = √AB² - BE²

BE = BD/2 = 16/2 = 8 cm

AE = √17² - 8²

= √289 - 64

= √225

AE = 15 cm

AC = 2AE = 30 cm

A(ABCD) = AC×BD/2 = 30×16/2 = 30×8 = 240 cm²