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Scale Factor. M7G3: Students will use the properties of similarity and apply these concepts to geometric figures. Scale Factor (Using Rules). Multiply. Multiply x and y by a whole number will enlarge the shape. Multiply x and y by a fraction will shrink the shape.
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Scale Factor M7G3: Students will use the properties of similarity and apply these concepts to geometric figures.
Scale Factor (Using Rules) Multiply • Multiply x and y by a whole number will enlarge the shape. • Multiply x and y by a fraction will shrink the shape. • Multiply a number with x and the width will change. • Multiply a number with y and the height will change. (x, y) • A rule is applied to a coordinate pair to enlarge or shrink a shape and to translate a shape to a new position. Add • Adding or subtracting a number to x and y will change the location of the shape on the coordinate graph. • Adding to x moves the shape to the right. • Subtracting from x moves the shape to the left. • Adding to y moves the shape up. • Subtracting from y moves the shape down.
Rule Examples • Explain what would happen to a figure if you transformed it using the given rule. • (15x, 20y) • (3x, 9y – 5) • (x – 4, 4y) • (6x + 7, 6y + 2) • (¼x, ¼y)
Scale Factor Ratio • The ratio of corresponding side lengths. The number that is multiplied by the side lengths to produce a new shape. • A comparison of two quantities, usually expressed as a fraction. Corresponding Side Lengths • Side lengths in two different shapes that are in the same position. Corresponding Angles • Angles in two different shapes that are in the same position. Similar Figures • Two shapes that have the same shape but not the same size.
How to find Scale Factor • When a figure is dilated, its size is changed by multiplying the length of each side by a scalefactor. All angles remain the same and so the new shape (or image) is similar to the original. • Can be found by dividing a new side length by the original side length. • When going from a small shape to a larger shape the scale factor is greater than 1. • When going from a large shape to a smaller shape the scale factor is less than 1. • Determine the corresponding side lengths. • Determine if you are making a larger shape or a smaller shape. • Determine if the scale factor is greater than or less than 1. • Right the correct ratio.
How is the perimeter and area of a figure affected by the scale factor? • Perimeter Scale Factor is the same as the scale factor. • Area Scale Factor is the scale factor squared.