1. The diagonals of a quadrilateral intersect at right angles. The lengths of the diagonals are 16 cm and 13 cm respectively. Calculate the area (in cm2) of the quadrilateral.   Hint Hint       2. Calculate the area (in cm2) of a trapezoid whose parallel sides are 20 cm and 30 cm respectively and the distance between them is 9 cm.   Hint       3. If the perimeter of a rhombus is 68 cm, calculate its area (in cm2) given that its one diagonal is 30 cm.   Hint       4. Find the area (in cm2) of a parallelogram whose base is 42 cm and height is 9 cm.   Hint       5. If the area of a trapezoid is 243 m2 and its parallel sides are 15 m and 12 m, find the distance (in m) between them.   Hint       6. If two adjacent sides of a parallelogram are 10 cm and 20 cm and the distance between the shorter sides is 16 cm, calculate the distance (in cm) between the longer sides.   Hint       7. The longer diagonal of a four-sided playground is 100 m. If the lengths of the perpendiculars from the opposite vertices to this diagonal are 11.2 m and 18.8 m respectively, calculate the area (in m2) of the playground.   Hint