Shape and Space – Area for 2D Shapes

Area for 2D Shapes

Parallelogram:

. Formula → base x height

. base → length of bottom side

. height → perpendicular length from bottom to top

Trapezium:

. A 2D shape where one pair of opposite sides are parallel

. Formula → (a + b) / 2)) x height

. a and b → the top and bottom sides

. height → perpendicular length from a to b

Kite:

. Kite → a 2D shape with two equal adjacent sides with a line of symmetry from B to D

. Formula → ½ x BD x AC

. BD and AC are both diagonal lengths

Example 1:

Q) In a trapezium the base is 10cm and the height is 15cm. If the area of the trapezium is 90cm², what is the length of X?

1. Substitute the values given into the formula → (a + b) / 2)) x height
2. To workout X, keep it by itself on one side of the equation → divide by 15 on both sides to move it to the right side 90 ÷ 15 = 6, multiply both sides by 2 to move it to the right side, 6 x 2 = 12 and subtract 10 from both sides

A) 2cm

Example 2:

Q) What is the area of the kite if the lengths of the diagonals are 10cm and 15cm

1. Substitute values into the formula → ½ x BD x AC
2. Multiply the values → ½ x 10 x 15 = 75cm²

A) 75cm²