Similar Polygons
1. The problem asks for the ratio between the areas of two similar polygons given the ratio of their perimeters is 4 : 9.
2. For similar polygons, the ratio of their areas is the square of the ratio of their corresponding sides or perimeters.
3. Given perimeter ratio = 4 : 9, area ratio = $4^2 : 9^2 = 16 : 81$.
4. So, the correct answer is (d) 16 : 81.
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1. Given $\triangle ABC \sim \triangle XYZ$ and $AB = 3 \times XY$, find $\frac{a(\triangle XYZ)}{a(\triangle ABC)}$.
2. The ratio of corresponding sides is $AB : XY = 3 : 1$.
3. Area ratio is the square of side ratio, so $\frac{a(\triangle ABC)}{a(\triangle XYZ)} = 3^2 : 1^2 = 9 : 1$.
4. Therefore, $\frac{a(\triangle XYZ)}{a(\triangle ABC)} = \frac{1}{9}$.
5. The correct answer is (d) 1/9.
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1. Given the ratio of areas of two similar polygons is 9 : 49, find the ratio of their corresponding sides.
2. The ratio of areas = square of ratio of sides.
3. So, side ratio = $\sqrt{9} : \sqrt{49} = 3 : 7$.
4. The correct answer is (a) 3 : 7.
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1. Given lengths of two corresponding sides are 7 cm and 11 cm, find the ratio of their perimeters.
2. The ratio of perimeters is the same as the ratio of corresponding sides.
3. So, perimeter ratio = $7 : 11$.
4. The correct answer is (c) 7/11.
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1. Given the ratio of corresponding sides of two similar triangles is 2 : 5 and area of the first triangle is 16 cm², find the area of the second triangle.
2. Area ratio = square of side ratio = $2^2 : 5^2 = 4 : 25$.
3. Let area of second triangle be $x$, then $\frac{16}{x} = \frac{4}{25}$.
4. Solving for $x$, $x = \frac{16 \times 25}{4} = 100$ cm².
5. The correct answer is (c) 100.
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1. Given lengths of corresponding sides are 12 cm and 16 cm, and area of smaller polygon is 135 cm², find the area of the greater polygon.
2. Side ratio = $12 : 16 = 3 : 4$.
3. Area ratio = square of side ratio = $3^2 : 4^2 = 9 : 16$.
4. Let area of greater polygon be $x$, then $\frac{135}{x} = \frac{9}{16}$.
5. Solving for $x$, $x = \frac{135 \times 16}{9} = 240$ cm².
6. The correct answer is (c) 240.