The bases of the trapezoid are 142 cm and 89 cm, and the diagonals are 120 cm and 153 cm. Calculate the area of the trapezoid.
The Pythagorean theorem for the triangle AFC:
h2+(89+x)2=1202
h2=1202-(89+x)2
The Pythagorean theorem for the triangle EBD:
h2+(142-x)2=1532
h2=1532-(142-x)2
1202-(89+x)2=1532-142-x2
14400-7921+178x+x2=23409-20164-284x+x2
14400-7921-178x-x2=23409-20164+284x-x2
-178x-284x=23409-20164-14400+7921
-462x=-3234 |·-1
462x=3234
x=3234 462
x=7
x+89+y=142
y=142-x-89
y=142-7-89
y=46
h2=1202-(89+x)2=1202-89+72=1202-962
h2=14400-6724=5184
h=5184
h=72
A=AAED+AEFCD+AFBC
AAED=x·h2
AAED=7·722
AAED=7·722=7·2·362=7·36
AAED=252
AEFCD=b·h=89·72
AEFCD=6408
AFBC=y·h2
AFBC=46·722=2·23·722=23·72
AFBC=1656
A=AAED+AEFCD+AFBC=252+6408+1656
A=8316
Diagonala pravougaonika
Površina pravougaonika
Pitagorina teorema
Area of a right triangle
A=8316 cm2