ABCD is a parallelogram. Find the ratio of the area of the triangle ABC to the area of the parallelogram ABCD.

 
                Answer: 
            
        1:2
 We know that the opposite sides of a parallelogram are equal in length. So in triangles BCA and DCA:
 AD = BC (Opposite sides of a parallelogram)
 BA = CD (Opposite sides of a parallelogram)
 AC = AC (Common side)
 We may say that all the sides of these two triangles are equal.
- This also means that the area of both the triangles is equal which is equal to half the area of the parallelogram.
- This means the ratio of the area of triangle ABC to the parallelogram ABCD will be 1:2.
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