In a trapezium ABCD,AB||DC,AB=a cm,and DC=b cm.If M and N are the midpoints of the nonparallel lines,AD and BC respectively then find the ratio of ar(DCNM) and ar(MNBA).
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Solution
Construction: Draw a perpendicular from point D to the opposite side AB, meeting AB at Q and MN at P. Let length DQ = h Given, M and N are the midpoints of AD and BC respectively. So, MN || AB || DC and MN = 1/2AB+DC=a+b/2 M is the mid point of AD and MP || AB so by converse of mid point theorem, MP || AQ and P will be the mid point of DQ. arDCNM=1/2×DPDC+MN