Lesson 9 1 Area of 2 D Shapes

Lesson 9 -1 Area of 2 -D Shapes Lesson 9 -1: Area of 2 -D Shapes 1

Squares and Rectangles Area of Square: A = s² Example: 6 A = LW s A = 6² = 36 sq. units W L Example: s 6 Area of Rectangle: A = LW 5 12 A = 12 x 5 = 60 sq. units Lesson 9 -1: Area of 2 -D Shapes 2

Circles and Sectors Area of Circle: A = r² A 9 cm r 120° arc B r C Example: A = (9)² = 81 sq. cm Lesson 9 -1: Area of 2 -D Shapes 3

Triangles and Trapezoids h is the distance from a vertex of the triangle perpendicular to the opposite side. h b h is the distance from b 1 to b 2, perpendicular to each base b 2 h h b 1 b Lesson 9 -1: Area of 2 -D Shapes 4

Example: Triangles and Trapezoids 12 8 7 6 6 Lesson 9 -1: Area of 2 -D Shapes 5

Parallelograms & Rhombi Area of Parallelogram: A = b h h b Example: 8 Example: 6 10 9 A = 9 x 6 = 54 sq. units A = ½ (8)(10) = 40 sq units Lesson 9 -1: Area of 2 -D Shapes 6

Area of Regions The area of a region is the sum of all of its non-overlapping parts. 8 10 4 8 14 12 A = ½(8)(10) A = (12)(10) A = (4)(8) A = (14)(8) A= 40 A= 120 A=32 A=112 Area = 40 + 120 + 32 + 112 = 304 sq. units Lesson 9 -1: Area of 2 -D Shapes 7

Areas of Regular Polygons If a regular polygon has an area of A square units, a perimeter of P units, and an apothem of a units, then A = ½ (a)(p). Perimeter = (6)(8) = 48 8 apothem = Area = ½ (48)( Lesson 9 -1: Area of 2 -D Shapes )= sq. units 8