1 cm

Area is the number of unit squares needed to cover a region or surface. Area

1 cm 2 cm Area: 2 cm 2

Area: 6 cm 2 2 cm 3 cm

4 cm Area: 12 cm 2 3 cm

An altitude of a polygon is the segment from a vertex perpendicular to the opposite side. Altitude

Height is the length of an altitude of a polygon and is represented by h. Height

Formula: Area of a Rectangle A = bh The area of a rectangle (A) is equal to the base (b) times the height (h). This formula is often written as A = lw, where l is the length and w is the width.

Formula: Area of a Square A = s 2 The area of a square (A) is equal to the square of a side (s).

Example 1 Find the area of the following quadrilateral: a square 4.2 cm on a side. A = bh or s 2 = cm 2

Example 1 Find the area of the following quadrilateral: a rectangle with sides of 8.5 in. and 4 in. A = bh = 34 in. 2

What is the area of a square whose length is 7 units? Example 49 units 2

What is the length of a side of a square whose area is 225 units 2 ? Example 15 units

What is the area of a rectangle with a width of 15 units and a length of 20 units? 300 units 2 Example

What is the width of a rectangle if its area is 240 units 2 and its length is 20 units? Example 12 units

Formula: Area of a Parallelogram A = bh The area of a parallelogram (A) is equal to the base (b) times the height (h).

Altitudes are always to the base.

Find the area of the parallelogram. A = bh = 12(6.6) 6.6 m 12 m 8 m Example 2 = 79.2 m 2

Find the area of the parallelogram. A = bh Example = 19(6) = 114 units 2

Find the height of a rectangle that is 6 m long and has an area of 75 m 2. A = bh 75 = 6h A = 75 m 2 A = 75 m 2 6 m Example 3 h = 12.5 m

150 − x 2 Write the expression for the area of the following. 10 x x 15 x x Exercise

y Write the expression for the area of the following. 10 y y Exercise