1. The base of a triangle is twice its altitude. If the area of the triangle is 144 cm², find its base (in cm).   Hint Hint       2. 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       3. 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       4. Find the length of the hypotenuse (in cm) of an isosceles right-angled triangle having area of 484 cm².   Hint       5. 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       6. If the area of an equilateral triangle is 36√3 cm², find its perimeter (in cm).   Hint       7. Find the area (in m²) of an isosceles triangle, each of whose sides is 10 m and base 12 m.   Hint