Area of 2-Dimensional Figures

Area The area of a figure is the number of square units the figure encloses. Area of a rectangle = base · height

What is the area of the basketball court? Area of a Rectangle What is the area of the basketball court?

Find the area of the rectangle. Area of a Rectangle Find the area of the rectangle. 1 2 ft 4 __ 1

Area of a Square A square is a special type of rectangle. Because the base and height of a square are the same, you can find the area of a square by using the formula A= s , where A represents the area and s represents a side length. 2

Area of a Square 2 The booklet in a CD case is a square with side length 4 in. What is the area of the booklet?

Area 3 The area of a rectangular carpet is 54ft . The carpet is 9 ft long. How wide is the carpet? 2

Composing Shapes To compose a shape, join two (or more) shapes so there is no gap or overlap. You can compose a rectangle from a right triangle. To compose a rectangle, first make a copy of the right triangle. Rotate the copy and then push the triangles together to form a rectangle. So you can use a right triangle to compose a rectangle with the same base and height as the right triangle.

What is the area of the right triangle shown? Area of Right Triangles What is the area of the right triangle shown? 4

Area of Right Triangles The flower garden has the shape of a right triangle. What is the area of the flower garden? 5

Area of Right Triangles You can divide any rectangle into two right triangles. How is knowing this useful? The area of one of the right triangles is half the area of the rectangle. So if you can find the area of a rectangle, you don’t need the formula for the area of a right triangle.

Decomposing Shapes To decompose a shape, break it up to form other shapes. You can decompose a parallelogram to form a rectangle. Suppose you have a parallelogram with base, b, and height, h. To decompose the parallelogram into a rectangle, cut the parallelogram along its height. Move the triangle to the other side. Then push the pieces together to form a rectangle. So you can decompose a parallelogram to form a rectangle with the same base and height as the parallelogram.

Area of a Parallelogram Find the area of the parallelogram by decomposing the parallelogram into a rectangle. So what is the formula for the area of a parallelogram?

Area of a Parallelogram Find the area of the parallelogram by decomposing the parallelogram into a rectangle.

What is the area of the parallelogram? Area of Parallelograms What is the area of the parallelogram? 6

Formulas Rectangles: A = LW Squares: A = s² ​ Triangles: bh __ 2 Rectangles: A = LW Squares: A = s²
​ Triangles: A = 1/2 bh or A = Parallelograms: A = bh

Area of Polygons A polygon is a closed figure formed by three or more line segments that do not cross.

Area of Trapezoids (b + b )*h 1 2 __ h Base 1 Base 2

What is the area of the trapezoid? Area of Trapezoids What is the area of the trapezoid? 7

What is the area of the trapezoid? Area of Trapezoids What is the area of the trapezoid? 8 3 in. 12 in. 4 in.

Regular Polygons 6*( bh) __ 1 A = 2 A regular polygon is a polygon with all sides of equal length and all angles of equal measure. You can decompose a regular polygon to find its area. You can decompose a regular hexagon into 6 equilateral triangles to find its area. Find the area of one triangle, multiple the area by six to find the area of the hexagon. 6*( bh) __ 1 2 A =

Area of Hexagons Decompose the regular hexagon into six matching triangles to find the area of the hexagon. 9

Area of Hexagons Decompose the regular octagon into eight equilateral triangles to find the area of the octagon. Round your answer to the nearest whole number.

HW: Area of 2D Figures Worksheet

1 1/2 m 3/6 mi 1.2 cm 1/8 mi 3.4 cm 1/4 mi 2.5 in 2 cm 3/4 m 1.4 cm