Area Problems The length of each side of an equilateral triangle having an area of 4?3 cm 2 is? 4 cm 3 cm ?3/4 cm 4/?3 cm 4 cm 3 cm ?3/4 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 The length of a rectangular plot is twice of its width. If the length of a diagonal is 9?5 meters, the perimeter of the rectangular is? 27 m 54 m 81 m None of these 27 m 54 m 81 m None of these ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let breadth = y meters,Then, length = 2y meters? Diagonal = ?y2 + (2y)2 = ?5y2 metersSo, ?5y2 = 9 ?5? y= 9Thus, breadth = 9 m and length = 18 m? Perimeter = 2 (18 + 9) m = 54m.
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 The length and breadth of a square are increased by 40% and 30% respectively. The area of a resulting rectangle exceeds the area of the square by? None of these 42% 62% 82% None of these 42% 62% 82% ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let the side of the square = 100 m So area of square = 100 x 100 = 10000.New length = 140 m, New breadth = 130 mIncrease in area = [(140 x 130) - (100 x 100)] m2= 8200 m2? Required increase percent = (8200/ 10000) x 100 % = 82%
Area Problems An error 2% in excess is made while measuring the side of a square. The percentage of error in the calculated area of the square is: 4% 4.04% 2% 2.02% 4% 4.04% 2% 2.02% ANSWER EXPLANATION DOWNLOAD EXAMIANS APP 100 cm is read as 102 cm. ∴ A1 = (100 x 100) cm2 and A2 (102 x 102) cm2. (A2 - A1) = [(102)2 - (100)2] = (102 + 100) x (102 - 100) = 404 cm2. ∴ Percentage error = ❨ 404 x 100 ❩% = 4.04%
Area Problems A circular disc of area 0.49 ? square meters, rolls down a length of 1.76 km. The number of revolutions it makes is? 400 600 300 4000 400 600 300 4000 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Area = ?r2 = 0.49? ? r = 0.7 mNumber of revolutions = total distance / circumference = (1.76 x 1000) / (2 x 22/7 x 0.7) = 400
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