Area and Perimeter
-  The area of a trapezium is 384 sq.cm2. If its parallel sides are in ratio 3 : 5 and the perpendicular distance between them be 12 cm, The smaller of parallel sides is ?
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                        View Hint View Answer Discuss in Forum Let the sides of trapezium be 5k and 3k, respectively 
 According to the question,
 (1/2) x [(5k + 3k) x 12] = 384Correct Option: BLet the sides of trapezium be 5k and 3k, respectively 
 According to the question,
 (1/2) x [(5k + 3k) x 12] = 384
 ⇒ 8k = (384 x 2)/12 = 64
 ⇒ k = 64/8 = 8 cm
 Length of smaller of the parallel sides = 8 x 3 = 24 cm
-  The circumference of a circle is 25 cm. Find the side of the square incribed in the circle.
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                        View Hint View Answer Discuss in Forum Circumference of the circle = 2πr = 25 
 ⇒ r = 25 / (2π)
 According to the formula,
 Side of inscribed square = r√2Correct Option: ACircumference of the circle = 2πr = 25 
 ⇒ r = 25 / (2π)
 According to the formula,
 Side of inscribed square = r√2
 = 25 / (2πr x √2)
 = 25 / (π√2 ) cm
-  If area of a square is 64 sq cm, then find the area of the circle formed by the same perimeter.
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                        View Hint View Answer Discuss in Forum Area of square = 64 sq cm 
 (Side)2 = 64
 ∴ Side = √64 = 8 cm
 According to the question,
 ⇒ 2πr = 4 x 8
 ⇒ r = (4 x 8)/2πCorrect Option: CArea of square = 64 sq cm 
 (Side)2 = 64
 ∴ Side = √64 = 8 cm
 According to the question,
 ⇒ 2πr = 4 x 8
 ⇒ r = (4 x 8)/2π
 ⇒ r = 16/π
 ∴ Area of the circle
 = π x (16/π) x (16/π) sq cm
 = 256/π sq cm.
-  The side of a square is 5 cm which is 13 cm less than the diameter of a circle. What is the approximate area of the circle ?
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                        View Hint View Answer Discuss in Forum Diameter of the circle = 13 + 5 = 18 cm 
 ∴ Radius = Diameter/2 =18/2 = 9 cm
 Area of the circle = πr2 = (22/7) x 92Correct Option: DDiameter of the circle = 13 + 5 = 18 cm 
 ∴ Radius = Diameter/2 =18/2 = 9 cm
 Area of the circle = πr2 = (22/7) x 92
 = (22 x 81)/9
 = 1782/7
 = 254.57 sq cm
 = 255 sq cm
-  The ratio of the area of the circumcircle and the incircle of a square is
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                        View Hint View Answer Discuss in Forum Ratio of the areas of the circumcircle and incircle of a square 
 = [(Diagonal)2π] / [(Side)2π]Correct Option: ARatio of the areas of the circumcircle and incircle of a square 
 = [(Diagonal)2π] / [(Side)2π]
 = [(Side x √2)2] / (Side)2 = 2/1 or 2 : 1
 
	