70 likes | 83 Views
This guide explains how to simplify ratios, solve for unknown values in ratios, and find the length and width of rectangles using ratios. Examples and step-by-step solutions are provided.
E N D
Example 1 Simplify Ratios Simplify the ratio. 60 cm : 200 cm a. b. SOLUTION a. 60 cm : 200 cm can be written as the fraction . 3 60 ÷ 20 Divide numerator and denominator by their greatest common factor, 20. = 10 200 ÷ 20 60 cm 60 cm 3 ft 200 cm 18 in. 200 cm 3 is read as “3 to 10.” Simplify. = 10
Example 1 Multiply. Divide numerator and denominator by their greatest common factor, 18. Simplify Ratios b. = Substitute 12 in. for 1 ft. = = = 3 ·12 in. 3 ft 36 ÷ 18 2 36 in. 18 in. 18 ÷ 18 1 18 in. 18 in. 2 Simplify. is read as “2 to 1.” 1
Example 2 Use Ratios In the diagram, AB : BC is 4 : 1and AC = 30. Find AB and BC. SOLUTION Let x = BC. Because the ratio of AB to BC is 4 to 1, you know that AB = 4x. AB + BC= AC Segment Addition Postulate 4x + x = 30 Substitute 4xfor AB,x for BC, and 30 for AC. 5x = 30 Add like terms. x = 6 Divide each side by 5.
Example 2 Use Ratios To find AB and BC, substitute 6 for x. AB = 4x = 4 ·6 = 24 BC = x = 6 So, AB = 24 and BC = 6. ANSWER
Example 3 Use Ratios The perimeter of a rectangle is 80 feet. The ratio of the length to the width is 7 : 3. Find the length and the width of the rectangle. SOLUTION The ratio of length to width is 7 to 3. You can let the length l = 7x and the width w = 3x. 2l + 2w= P Formula for the perimeter of a rectangle 2(7x) + 2(3x) = 80 Substitute 7x for l, 3x for w, and 80 for P. 14x + 6x = 80 Multiply. 20x = 80 Add like terms. x = 4 Divide each side by 20.
Example 3 Use Ratios To find the length and width of the rectangle, substitute 4 for x. l = 7x = 7 ·4 = 28 w = 3x = 3 ·4 = 12 The length is 28 feet, and the width is 12 feet. ANSWER
Checkpoint Use Ratios 1. In the diagram, EF : FG is 2 : 1 and EG = 24. Find EF and FG. 2. The perimeter of a rectangle is 84 feet. The ratio of the length to the width is 4 : 3. Find the length and the width of the rectangle. EF = 16;FG = 8 length, 24 ft; width, 18 ft ANSWER ANSWER