Area Problems If the radius of a circle is decreased by 50% , find the percentage decrease in its area. 65% 35% 25% 75% 65% 35% 25% 75% ANSWER EXPLANATION DOWNLOAD EXAMIANS APP let original radius = r and new radius = (50/100) r = r/2 original area = ?r 2 and new area = ? r / 2 2 decrease in area = 3 ?r 2 / 4 * 1 ?r 2 *100 = 75%
Area Problems If the radius of a circle be reduced by 50%. Its area is reduced by? 31.5% 39.5% 34.5% 65.5% 31.5% 39.5% 34.5% 65.5% ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Original area = ? x (r/2)2 = ?r2/4Reduction in area = ? r2 - 3? r2/4? Reduction per cent = [ 3?r2/4 x 4/(?r2) x 100 ] %= 75%
Area Problems If the diagonal of a rectangle is 17cm long and its perimeter is 46 cm. Find the area of the rectangle. 130 140 110 120 130 140 110 120 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP let length = x and breadth = y then 2(x+y) = 46 => x+y = 23 x²+y² = 17² = 289 now (x+y)² = 23² => x²+y²+2xy= 529 => 289+ 2xy = 529 => xy = 120 area = xy = 120 sq.cm
Area Problems One side of a rectangular field is 4 meter and its diagonal is 5 meter. The area of the field is? 20 m 2 4?5 m2 12 m2 15 m2 20 m 2 4?5 m2 12 m2 15 m2 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Other side = ?5 2 - 42 = ? 9=3 mSo The area of the rectangular field = 4 x 3 = 12 m2
Area Problems The area of the sector of a circle, whose radius is 12 meters and whose angle at the centre is 42, is? 39.6 sq. meters 52.8 sq. meters 26.4 sq. meters 79.2 sq. meters 39.6 sq. meters 52.8 sq. meters 26.4 sq. meters 79.2 sq. meters ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Area of the sector = [(22/7) x 12 x 12] x [42°/360°] m2 = 52.8 m2
Area Problems The area of a rectangular field is 15 time the sum of its length and breadth. If the length of that field is 40 m, what is the breadth of that field? 24 m 32 m 28 m 25 m 24 m 32 m 28 m 25 m ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Length ot rectangle = 40 mLet breadth of = kThen, according of the question, (40 + k)15 = 40k ? 600 + 15k = 40k ? 25k = 600? k = 24 m
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