AREA OF TRIANGLES AND RECTANGLES Rectangles Area length

AREA OF TRIANGLES AND RECTANGLES Rectangles Area = length x width Triangles l w Area = ½ x base x height h b

Example: Find the area of the following shape Area A = l x w = 8 x 6 = 48 cm 2 Area B= ½ x b x h =½x 8 x 5 = 20 cm 2 Total area = 68 cm 2 8 cm A 6 cm B 5 cm

AREA OF A PARALLELOGRAM A parallelogram is a quadrilateral with opposite sides parallel and equal to each other. Finding the formula for calculating the area of a parallelogram is straight forward.

Area of a parallelogram = base x height Area = b x h height base 1. 5 cm 12 cm Area = b x h = 12 x 5 = 60 cm 2

2. Calculate the size of the base. area = 63 cm 2 7 cm Area = base x height 63 = b Base = x 7 63 = 9 cm 7

Area of a trapezium A trapezium is a quadrilateral with just one pair of parallel sides. a a b b The parallel sides are usually labelled a and b

8 cm 6 cm 12 cm Area A = 1/2 b x h = 1/2 x 12 x 6 = 36 cm 2 Area B Total area = 60 cm 2 = 1/2 b x h = 1/2 x 8 x 6 = 24 cm 2

a and b are the lengths of the parallel sides. h is the perpendicular distance between sides a & b. a h b Area of a trapezium = ½ x (a + b) x h Area = ½ (a + b) h

Note: From the previous example a = 8, b = 12 and h = 6 cm. Area = ½ (a + b) h = 1/2 x (8 + 12) x 6 = 1/2 x 20 x 6 = 60 cm 2

7 cm 1. 6 cm 13 cm Area = = ½ (a + b) h ½ x (7 + 13) x 6 ½ x 20 x 6 60 cm 2

7. 5 cm 2. 5 cm 6. 5 cm A = ½ x (a+b) x h = ½ x 14 x 5 = 35 cm 2