Area Problems The radius of a circular field is 25 m. Find the area of the field. 625 ? sq m 125 ? sq m 135 ? sq m 25 ? sq m 625 ? sq m 125 ? sq m 135 ? sq m 25 ? sq m ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Required area = ?r2 = ? x 25 x 25 = 625? sq m.
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? 7 cm 5 cm 4 cm 6 cm 7 cm 5 cm 4 cm 6 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 diagonal of a rectangle is √41 cm and its area is 20 sq. cm. The perimeter of the rectangle must be: 20 cm 41 cm 18 cm 9 cm 20 cm 41 cm 18 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 perimeter of an equilateral triangle is 90 cm. Find its area. 250?3 sq cm 135?3 sq cm 225?3 sq cm 151?3 sq cm 250?3 sq cm 135?3 sq cm 225?3 sq cm 151?3 sq cm ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Given that, perimeter = 90 cm? 3a = 90 cm [a = side]? a = 90/3 = 30 cm? Area = ?3a2 / 4 = ?3/4 x (30)2= 900 x ?3/4 = 225?3 sq cm
Area Problems A rectangular carpet has an area of 120 sq. m and a perimeter of 46 m . The length of its diagonal is? 20 m 15 m 17 m 16 m 20 m 15 m 17 m 16 m ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let length = a metres and breadth = b metres Then, 2(a+b)= 46 ? (a+b) =23 and ab =120 ? Diagonal = ?a2 + b2?(23)2-2 x 120?289 = 17 m
Area Problems The length of a rectangle is halved, while its breadth is tripled. What is the percentage change in area? 25% increase 50% increase 75% decrease 50% decrease 25% increase 50% increase 75% decrease 50% decrease ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let original length = x and original breadth = y. Original area = xy. New length = x . 2 New breadth = 3y. New area = ❨ x x 3y ❩ = 3 xy. 2 2 ∴ Increase % = ❨ 1 xy x 1 x 100 ❩% = 50%
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