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Aflati aria paralelogramului ABCD daca AB=BD=5cm iar BC=6cm.

Răspuns :

AB=BD=5    AB=DC=5
BC=6
ducem BM_I_DC
notam MC=x
DM=5-x
MB²=6²-x²
MB²=5²-(5-x)²
6²-x²=5²-(5-x)²
36-x²=25-25+10x-x²
36=10x
x=3,6
MB²=6²-x²=36-3,6²=23,04
MB=4,8 cm
A=5×4,8=24 cm²