140 likes | 330 Views
Starter Questions. Similar Figures. Learning Intention. To explain how the scale factor applies to similar figures. Similar Figures. shapes are similar only when. Corresponding sides are in proportion. AND. Corresponding angles are equal.
E N D
Similar Figures Learning Intention • To explain how the scale factor applies to similar figures.
Similar Figures shapes are similar only when • Corresponding sides are in proportion AND • Corresponding angles are equal All these rectangles are not similar to one another since only condition 2 is true
Similar Figures Corresponding sides are in proportion AND corresponding angles are equal Scale Factor Scale Factor is the number used as a multiplier in enlarging / reducing shapes To calculate the scale factor In similar shapes… …divide the length by length, and where possible breadth by breadth
Similar Figures The rectangles below are similar: Find the enlargement scale factor that maps A to B 16cm 8cm A B 5cm 10cm E.S.F = 16 ÷ 8 = 2 E.S.F will always be greater than 1
Similar Figures The rectangles below are similar: Find the enlargement scale factor that maps A to B 12cm 8cm A B 5cm 7.5cm E.S.F = 12 ÷ 8 = 1.5 E.S.F will always be greater than 1
Similar Figures If we are told that two objects are similar, and we can calculate the scale factor, then we can calculate the value of an unknown side These 3 rectangles are similar. Find the unknown sides A B C 8cm 24cm ycm 3cm xcm 13.5cm
Similar Figures If we are told that two objects are similar, and we can calculate the scale factor, then we can calculate the value of an unknown side These 3 rectangles are similar. Find the unknown sides A B C 5.6cm xcm 26.88cm 2.1cm 7.14cm ycm
Similar Figures Scale Factor applies to ANY SHAPES that are mathematically similar. 1.4 cm 7 cm 2cm y z 3 cm 15 cm 6 cm Given the shapes are similar, find the values y and z ?
Similar Figures Scale Factor applies to ANY SHAPES that are mathematically similar. b 7.5 cm a 4 cm 3 cm 8 cm 2cm 10 cm Given the shapes are similar, find the values a and b ?
Similar Figures The rectangles below are similar: Find the reduction scale factor that maps B to A 20cm 5cm A B 3cm 12cm R.S.F will always be less than 1
Similar Figures If we are told that two objects are similar, and we can calculate the scale factor, then we can calculate the value of an unknown side These 2 rectangles are similar. Find the unknown sides A B x mm 28mm 4mm 16mm
Similar Figures Now try Ex 5.1 Ch 4 Pg 75