Area Problems The area of rectangle whose length is 5 more than twice its width is 75 sq units. What is the perimeter of the rectangle? 40 unit 20 unit 24 unit 30 unit 40 unit 20 unit 24 unit 30 unit ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let the width of the rectangle = k units? Length = (2k + 5) units.According to the question,Area = k(2k + 5)? 75 = 2k2 + 5k? 2k2 + 5k - 75 = 0 ? 2k2 + 15k - 10k - 75 = 0 ? k(2k + 15) - 5(2k + 15) = 0 ? (2k + 15) (k - 5) = 0 ? k = 5 and -15/2Width cannot be negative. ? Width = 5 units? Length = 2x + 5 = 2 x 5 + 5 = 15 unit? perimeter of the rectangle = 2(15 + 5) = 40 units
Area Problems In a triangle ABC, BC = 5 cm AC = 12 cm and AB = 13 cm. The length of a altitude drawn from B on AC is? 6 cm 7 cm 4 cm 5 cm 6 cm 7 cm 4 cm 5 cm ANSWER EXPLANATION DOWNLOAD EXAMIANS APP ? s= (13 + 5 + 12) / 2 cm = 15cms-a = 2 cm, s-b = 10 cm and s-c = 3 cm ? Area = ? (15 x 2 x 10 x 3 ) cm2= 30 cm2? (12 x h) / 2 = 30 ? h = 5 cm
Area Problems The cost of papering the four walls of a room is Rs. 48. Each one of length, breadth and height of another room is double that of this room.The cost of papering the walls of the new room is? Rs. 384 Rs. 96 Rs. 298 Rs. 192 Rs. 384 Rs. 96 Rs. 298 Rs. 192 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let the length, breadth and height of the room be l, b and h respectively As per question Cost of 2(l + b) x h = Rs. 48 ? Required cost = cost of 2 (2l + 2b) x 2h= cost of 4 [2(l + b) x h ]= 4 x Rs. 48= Rs. 192
Area Problems The area of a right angled triangle is 10 sq cm. If its perpendicular is equal to 20 cm, find its base. 3 cm 1 cm 2 cm 4 cm 3 cm 1 cm 2 cm 4 cm ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Given that, area = 10 sq cm, perpendicular = 20 cm and base = ? area = (base x Perpendicular) / 2 ? 10 = (base x 20) / 2 ? base = 1 cm
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 19.8 cm 21.6 cm 26.4 cm 13.2 cm 19.8 cm 21.6 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 ratio of the radii of two circle is 1:3 the radio of their areas is? 1:3 None of these 1:6 1:9 1:3 None of these 1:6 1:9 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
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