Răspunsuri

  • Utilizator Brainly
2014-02-26T11:53:35+02:00
AC perpendicular pe CB ⇒ CB²=AB²-AC²=256-144=112 ⇒ CB=AD=√112=4√7 cm.
Ducem CE perpendicular pe AB:
ΔACB asemenea cu ΔCBE(<B comun, <ACB=<CEB=90) ⇒ CE/AC=CB/AB=BE/BC ⇒
CE=AC·CB/AB=12·4√7/16=3√7 cm.
In ΔCBE, BE²=CB²-CE²=112-63=49 ⇒ BE=7 cm ⇒ CD=AB-2BE(trapez isoscel)=2 cm.
P(ABCD)=16+2+2·4√7=18+8√7 cm.
A(ABCD)=(AB+CD)·CE/2=27√7 cm².
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