1. The lengths of the sides of a triangle are in the ratio 3 : 4 : 5 and its perimeter is 72 cm. Find the area (in cm²) of the triangle.   Hint Hint       2. Find the area (in m²) of an isosceles triangle, each of whose sides is 10 m and base 12 m.   Hint       3. The area of a right-angled triangle is 30 times its base. What is its height (in cm)?   Hint       4. The ratio of the areas of two triangles is 2 : 3. The ratio of their heights is 3 : 2. If the ratio of their bases is 4 : y, what is y?   Hint       5. Calculate the area (in cm² upto 1 decimal place) of an equilateral triangle of side 10 cm.   Hint       6. The base of a triangular field is five times its height. If the cost of cultivating the field at $32 per hectare is $500, find its height (in m). Note that 1 hectare = 10000 m2.   Hint       7. Find the area (in cm²) of a triangle with base 12 cm and height 7 cm.   Hint