How to find perimeter and area of rectangles and squares, and circumference and area of circles. Chapter 1.9GeometryStandard/Goal: 1.1, 1.3, 2.2

1. Check and discuss assignment from Friday. 2. Read, write, and discuss how to find perimeters of rectangles and squares, and circumferences of circles. 3. Read, write, and discuss how to find areas of rectangles, squares, and circles. 4. Work on assignment.

Square with side length s Perimeter: P = 4 s Area: A = s²

Rectangle with base b and height h Perimeter: P = 2 b + 2 h Area: A = bh

Circle with radius r and diameter d Circumference: C = d or C = 2 r Area: A = r²

Margaret’s garden is a square 12 ft on each side. Margaret wants a path 1 ft wide around the entire garden. What will the outside perimeter of the path be? The perimeter is 56 ft. P = 4 s Formula for perimeter of a square P = 4(14) = 56Substitute 14 for s. Because the path is 1 ft wide, increase each side of the garden by 1 ft. s = = 14

C = 2 (6.5)Substitute 6.5 for r. The circumference of G is 13, or about 40.8 cm.. C = 13 Exact answer C = Use a calculator. C = 2 r Formula for circumference of a circle G has a radius of 6.5 cm. Find the circumference of G in terms of. Then find the circumference to the nearest tenth...

Quadrilateral ABCD has vertices A (0, 0), B (9, 12), C (11, 12), and D (2, 0). Find the perimeter. Draw and label ABCD on a coordinate plane. BC = |11 – 9| = |2| = 2Ruler Postulate DA = |2 – 0| = |2| = 2Ruler Postulate Find the length of each side. Add the lengths to find the perimeter. AB =(9 – 0) 2 + (12 – 0) 2 = Use the Distance Formula. = = 255 = 15 CD = (2 – 11) 2 + (0 – 12) 2 = ( (–9) 2 + (–12) 2 Use the Distance Formula. = = 255 = 15

(continued) Perimeter= AB + BC + CD + DA = = 34 The perimeter of quadrilateral ABCD is 34 units.

Write both dimensions using the same unit of measurement. Find the area of the rectangle using the formula A = bh. 36 in. = 3 ftChange inches to feet using 12 in. = 1 ft. A = bh Formula for area of a rectangle. A = (4)(3)Substitute 4 for b and 3 for h. A = 12 You need 12 ft 2 of fabric. To make a project, you need a rectangular piece of fabric 36 in. wide and 4 ft long. How many square feet of fabric do you need?

A = r 2 Formula for area of a circle. A = (1.5) 2 Substitute 1.5 for r. A = 2.25 In B, r = 1.5 yd.. The area of B is 2.25 yd 2.. Find the area of B in terms of..

If two figures are congruent, Then their areas are equal.

The area of a region is the sum of the areas of its nonoverlapping parts.

Find the area of the figure below. Draw a horizontal line to separate the figure into three nonoverlapping figures: a rectangle and two squares.

A R = bh Formula for area of a rectangle A R = (15)(5)Substitute 15 for b and 5 for h. A R = 75 A S = s 2 Formula for area of a square A S = (5) 2 Substitute 5 for s. A S = 25 A = Add the areas. A = 125 The area of the figure is 125 ft 2. Find each area. Then add the areas. (continued)

Kennedy, D., Charles, R., Hall, B., Bass, L., Johnson, A. (2009) Geometry Prentice Hall Mathematics. Power Point made by: Robert Orloski Jerome High School.