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? 21.6 cm 26.4 cm 19.8 cm 13.2 cm 21.6 cm 26.4 cm 19.8 cm 13.2 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 if the side of a square be increased by 4 cms. The area increased by 60 sq. cms . The side of the square is? None of these 13 cm 12 cm 14cm None of these 13 cm 12 cm 14cm ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let each side = x cmThen, (x + 4 )2 - x2 = 60? x 2 + 8x + 16 - x2 = 60? x = 5.5 cm
Area Problems The diagonal of a rectangle is √41 cm and its area is 20 sq. cm. The perimeter of the rectangle must be: 18 cm 41 cm 20 cm 9 cm 18 cm 41 cm 20 cm 9 cm ANSWER EXPLANATION DOWNLOAD EXAMIANS APP √l2 + b2 = √41. Also, lb = 20. (l + b)2 = (l2 + b2) + 2lb = 41 + 40 = 81 ⟹ (l + b) = 9. ∴ Perimeter = 2(l + b) = 18 cm
Area Problems The radius of a circle is so increased that its circumference increased by 5%. The area of the circle, then increases by 12.5% 10.25% 10.5 % 11.25% 12.5% 10.25% 10.5 % 11.25% ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Increase in circumference of circle = 5%? Increase in radius is also 5%.Now, increase in area of circle = 2a + (a2/100) %Where, a = increase in radius= 2 x 5 + (5 x 5)/100 % = 10.25%
Area Problems If 88 m wire is required to fence a circular plot of land, then the area of the plot is? None of these 616 m2 526 m2 556 m2 None of these 616 m2 526 m2 556 m2 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Circumference of circular plot= 88 m? 2 x (22/7) x r = 88? r = 88 x (7/22) x (1/2) = 14 m Now area = ?r2=( 22/7) x 14 x 14 m2= 616 m2
Area Problems The length of hall is (4/3) times its breadth. If the area of hall be 300 square meters, the difference between the length and the breadth is? None of these 3 meters 15 meters 4 meters None of these 3 meters 15 meters 4 meters ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let breadth = b meters.Then, length = 4b/3 meters.? b x 4b/3 = 300? b2 = 300 x 3/4 ? b2 = 225? b = 15Hence, required difference = [(Length) - (Breadth) ]= 4b/3 - b = b/3= 15/3 m= 5 m
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