Q89 of 131 Page 226

Perimeter of a parallelogram shaped land is 96 m and its area is 270 square metres. If one of the sides of this parallelogram is 18 m, find the length of the other side. Also, find the lengths of altitudes l and m (Fig. 9.42).

AB = DC =18 m


Perimeter of parallelogram ABCD = AB + BC + CD + DA


96 = 18 + BC + 18 + BC


(opposite sides of a parallelogram are equal)


2 BC = 96 – 36 = 60


BC = AD = 30 m


Given, area of parallelogram ABCD = 270 m2



We know that,


Area of a parallelogram = b × h (corresponding height)


Taking AB as the base,


AB × l = 270


18 × l = 270


l = 15 m


Taking AD as the base,


AD × m = 270


30 × m = 270


m = 9 m


Length of the other side = 30 m


Length of altitude l = 15 m


Length of altitude m = 9 m


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