Original circumference = 2?r New circumference = (150 /100) x 2 ?r = 3?r 2?R = 3?r? R = 3r/2 Original area = ?r2New area = ?R2= ?9r2 / 4 = 9?r2/4Increase in area = (9?r2/4 ) - (?r2)= (5/4) ?r2Req. increase per cent = [{(5/4) ?r2} / {?r2}] x 100 = 125 %
Let the breadth of the given rectangle be x then length is 2x. thus area of the given rect is 2 x 2 after dec 5cm from length and inc 5cm breadth , new lenght becomes 2x-5 and breadth is x+5.thus new area =(2x-5)(x+5)= 2 x 2 + 5 x - 25 since new area is 75 units greater than original area thus 2 x 2 + 75 = 2 x + 5 x - 25 5x=75+25 5x=100 therefore x=20 hence length of the rectangle is 40 cm.
Circular piece is 4 x 11 = 44 cm long, Then Circumference of circle is given by, 44 = pi x D, where D is the diameter D = 44 / pi Take pi = 22 / 7, then D = 44 / (22/7) = (44 x 7) / 22 D = 14 cm.
Given that, a = 8 cm, b = 10 cm and c = 12 cm We know, that s = (a + b + c)/2 = (8 + 10 + 12)/2= 30/2 = 15 cm ? (s - a) = (15 - 8) = 7 cm (s - b) = (15 - 10) = 5 cm (s - c) = (15 - 12) = 3 cm ? Area = ?s(s - a) (s - b) (s - c)= ?15 x 7 x 5 x 3= ?1575= ?25 x 63= 5?63 cm
EXAMIANS