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. Calculate the height (in cm to the nearest integer) of an equilateral triangle whose area is 36.95 cm².   Hint       3. Calculate the height (in cm) of a triangle whose base is 24 cm and area is 180 cm².   Hint       4. The area of a right-angled triangle is 30 times its base. What is its height (in cm)?   Hint       5. 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       6. 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       7. Find the area (in cm²) of a triangle with base 12 cm and height 7 cm.   Hint