# An arbitrary point E was chosen inside the parallelogram ABCD. Prove that the sum of the areas of the triangles BEC

May 31, 2020 | Education

| **An arbitrary point E was chosen inside the parallelogram ABCD. Prove that the sum of the areas of the triangles BEC and AED is equal to half the area of the parallelogram**

Draw a segment perpendicular to the sides AD and BC, passing through point E.

Parallelogram Area:

SABCD = AD * GF

AED Triangle Area:

SAED = AD * EF / 2

BEC Triangle Area:

SBEC = BC * EG / 2

AD = BC (according to the parallelogram property).

SBEC + SAED = BC * EG / 2 + AD * EF / 2 = AD * EG / 2 + AD * EF / 2 = (EG + EF) * AD / 2 = GF * AD / 2 = SABCD / 2

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