# NCERT Mathematics Class 9 Exemplar Ch 12 Heron's Formula Part 4

Exercise 12.3

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

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 Rs a year. A company hired one of its walls for 6 months. How much rent did it pay?

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.

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.

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.

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.

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

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.