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. Find the area (in m²) of an isosceles triangle, each of whose sides is 10 m and base 12 m.   Hint       3. 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       4. Calculate the area (in cm² upto 1 decimal place) of an equilateral triangle of side 10 cm.   Hint       5. The difference between the sides of a right-angled triangle containing the right angle is 7 cm and its area is 60 cm². Calculate the perimeter (in cm) of the triangle.   Hint       6. Calculate the height (in cm) of a triangle whose base is 24 cm and area is 180 cm².   Hint       7. 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