Q.If the quadrilateral formed by joining the midpoints of the sides of parallelogram ABCD has an area of 100 square cm, then what is the area of the parallelogram ABCD? (a) 400 sq cm (b) 200 sq cm (c) 600 sq cm (d) 800 sq cm
Answer: B
Let’s assume that when the midpoints of the sides of parallelogram ABCD are joined, a quadrilateral EFGH is formed. Join points E and G. E and G are the midpoints of AB and CD respectively. \(\therefore\) EG \(\parallel\) AD \(\therefore\) Parallelogram AEGD = 2 × \(\triangle\)EFG Similarly, Parallelogram ABCG = 2 × \(\triangle\)EHG \(\therefore\) Parallelogram AEGD + Parallelogram ABCG = 2 × \(\triangle\)EFG + 2 × \(\triangle\)EHG = 2 × [\(\triangle\)EFG + \(\triangle\)EHG] That is, Parallelogram ABCD = 2 × Quadrilateral EFGH = 2 × 100 sq cm = 200 sq cm
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