Area Problems If the radius of a circle is decreased by 50% , find the percentage decrease in its area. 35% 65% 25% 75% 35% 65% 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 In a circle of radius 21 cm an arc subtends an angle of 72° at the centre. The length of the arc is? 19.8 cm 26.4 cm 21.6 cm 13.2 cm 19.8 cm 26.4 cm 21.6 cm 13.2 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 If the sides of a rectangle are increased by 5%, find the percentage increase in its diagonals. 9% 5% 6% 4% 9% 5% 6% 4% ANSWER EXPLANATION DOWNLOAD EXAMIANS APP According to the formula,Percentage increase in diagonals = 5%
Area Problems The ratio of the area of square of side a and equilateral triangle of side a is? 2 : ?3 4 :3 2 :1 4 : ?3 2 : ?3 4 :3 2 :1 4 : ?3 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Ratio of area = a2/ ?(3/4) a2= 4/?3 = 4:?3
Area Problems In a rhombus, whose area is 144 sq.cmone of its diagonal is twice as long as the other, The lengths of its diagonals are? 6 cm, 12 cm 12 cm, 24 cm 6 ?2 cm, 12?2 cm 24 cm, 48 cm 6 cm, 12 cm 12 cm, 24 cm 6 ?2 cm, 12?2 cm 24 cm, 48 cm ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Area of rhombus = (d1 x d2) / 2? (d x 2d ) / 2 = 144? d2 = 144? d = 12 ? Length of diagonal = 12 cm, 24 cm
Area Problems The difference between the circumference and the radius of a circle is 37 cm. The area of a circle is? 154 sq. cm 148 sq. cm 111 sq. cm 259 sq. cm 154 sq. cm 148 sq. cm 111 sq. cm 259 sq. cm ANSWER EXPLANATION DOWNLOAD EXAMIANS APP ? 2?r - r = 37? [(2 x 22/7) -1]r= 37? 37r / 7= 37? r = 7 So, area of the circle =(22/7) x 7 x 7 cm2= 154 cm2
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