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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Let the sides of trapezium be 5k and 3k, respectively
According to the question,
(1/2) x [(5k + 3k) x 12] = 384Correct Option: B
Let 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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Circumference of the circle = 2πr = 25
⇒ r = 25 / (2π)
According to the formula,
Side of inscribed square = r√2Correct Option: A
Circumference 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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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: C
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)/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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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: D
Diameter 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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Ratio of the areas of the circumcircle and incircle of a square
= [(Diagonal)2π] / [(Side)2π]Correct Option: A
Ratio 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