Răspuns:
Explicație pas cu pas:
a)
Ducem CE⊥AB ( CE= inaltime)
DCEA= dreptunghi
DC=AE=9 cm
AD=CE
AB=AE+EB
16=9+EB
EB= 16-9
EB= 7cm
-
ABCD - trapez dreptunghic
AC⊥BD
↓
ABCD- trapez ortodiagonal ( diagonalele sunt perpendiculare)
CE= √b*B =√16*9=√144=12 cm
-
ΔCEB- ∡E=90°
CB²=CE²+EB²
CB²=12²+7²
CB²=144+49
CB²=193
CB=√193
-
AB²+CD²=AD²+BC²
16²+9²=12²+(√193)²
256+81=144+193
337=337
-
b)
Aabcd=[(B+b) *h]/2
AD= h (inaltime)
Aabcd= [(AB+CD)*AD]/2
Aabcd= [(16+9)*12] /2
Aabcd= (25*12)/2
Aabcd= 300/2
Aabcd= 150 cm²
