# NCERT Mathematics Class 9 Exemplar Ch 12 Heron՚s Formula Part 4 (For CBSE, ICSE, IAS, NET, NRA 2023)

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**Exercise 12.3**

Q. 1. Find the cost of laying grass in a triangular field of sides , and at the rate of ₹

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Q. 2. The triangular side walls of a flyover have been used for advertisements. The sides of the walls are , and The advertisements yield on earning of ₹ a year. A company hired one of its walls for 6 months. How much rent did it pay?

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Q. 3. From a point in the interior of an equilateral triangle, perpendiculars are drawn on the three sides. The lengths of the perpendiculars are , and Find the area of the triangle.

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Q. 4. The perimeter of an isosceles triangle is The ratio of the equal side to its base is Find the area of the triangle.

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Q. 5. Find the area of a parallelogram given in Fig. 12.2. Also find the length of the altitude from vertex A on the side DC.

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Q. 6. A field in the form of a parallelogram has sides and and one of its diagonals is long. Find the area of the parallelogram.

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Q. 7. The perimeter of a triangular field is and its sides are in the ratio Find the area of the triangular field.

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Q. 8. The sides of a quadrilateral ABCD are , , and (taken in order) respectively, and the angle between the first two sides is a right angle. Find its area.

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Q. 9. A rhombus shaped sheet with perimeter and one diagonal , is painted on both sides at the rate of ₹ Find the cost of painting.

Answer: ₹ 960

Q. 10. Find the area of the trapezium PQRS with height PQ given in Fig. 12.3

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