4) What is the perimeter of a rectangle whose length and breadth are 20 cm and 18 cm?

5) What is the area of a rectangle, whose length and breadth are 10cm and 8cm respectively?

6) What is the area of a right angled triangle having a base 10 cm and height 5 cm?

7) What is the primeter of scalene. Triangle having sides of 40mm, 20mm and 28mm?

8) What is the area of an equilateral triangle of side 450 mm?