Area Problems The ratio of the radii of two circle is 1:3 the radio of their areas is? 1:9 1:3 1:6 None of these 1:9 1:3 1:6 None of these ANSWER EXPLANATION DOWNLOAD EXAMIANS APP The Radio of areas = area of first circle : area of 2nd circle= ?r2 / ?(3r)2= ?r2/ 9 ?r2= 1/9 = 1: 9
Area Problems In a circle of radius 21 cm an arc subtends an angle of 72° at the centre. The length of the arc is? 13.2 cm 21.6 cm 19.8 cm 26.4 cm 13.2 cm 21.6 cm 19.8 cm 26.4 cm ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Arc length = 2?r (?° / 360°) = 2 x (22/7) x 21 x (72° / 360°) cm= 26.4 cm
Area Problems The length of each side of an equilateral triangle having an area of 4?3 cm 2 is? 3 cm ?3/4 cm 4 cm 4/?3 cm 3 cm ?3/4 cm 4 cm 4/?3 cm ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Area of equilateral triangle = ?3/4 a2 = 4?3.? a2 = 16? a = 4 cm
Area Problems If the side of a square is increased by 25%, then how much percent does its area get increased? 50 56.25 156.25 125 50 56.25 156.25 125 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let area 100 m2Then, side = 10 m New side = 125 % of 10= (125/100) x 10= 12.5 m New area = 12.5 x 12.5 m2=(12.5)2 sq. m? Increase in area = (12.5)2 - (10)2 m2= 22.5 x 2.5 m2=56.25 m2% Increase = 56.25 %
Area Problems The length of a rectangle is twice its breadth. If its length is decreased by 5 cm and the breadth is increased by 5 cm, the area of the rectangle is increased by 75 cm 2 . Therefore , the length of the rectangle is? 50 cm 20 cm 30 cm 40 cm 50 cm 20 cm 30 cm 40 cm ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let breadth = b, length = 2b? Area of rectangle = 2b x b = 2b2As per question. ? (2b - 5 ) (b + 5 ) = 2b2 + 75? 5b = 75 + 25? 5b = 100? b = 100 / 5 = 20Hence, length of the rectangle =2b = 2 x 20 = 40 cm.
Area Problems A rectangle has 15 cm as its length and 150 cm 2 as its area .Its area is increased to 1 1 / 3 times the original area by increasing only its length . Its new perimeter is? 60 cm 70 cm 80 cm 50 cm 60 cm 70 cm 80 cm 50 cm ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Breadth of the rectangle = (150/15) cm= 10 cmNew area = (4/3 x 150) cm2= 200 cm2New length = 200/10 cm=20 cmNew perimeters = 2(20 + 10) cm= 60 cm
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