Question 55
A rectangular field has an area of 20 sq. km. If the perimeter of the field is 18 km, what is the length of the longer side of the field?
Solution
Let length and breadth of field be $$l$$ and $$b$$ km
Perimeter = $$2(l+b)=18$$
=> $$l+b=9$$ ----------------(i)
Area = $$lb=20$$ ------------(ii)
Substituting value from equation (i), we get : $$l(9-l)=20$$
=> $$l^2-9l+20=0$$
=> $$(l-5)(l-4)=0$$
=> $$l=5,4$$
$$\therefore$$ Length of longest side = 5 km
=> Ans - (D)
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