Sec. 6–2 Similar Polygons

Figures that are similar (~) have the same shape but not necessarily the same size. Angles are congruent, Sides are proportional

Writing a similarity statement is like writing a congruence statement—be sure to list corresponding vertices in the same order. If two figures are similar, not only are their sides proportional, all their linear parts are proportional (such as the height, median, midsegment, diagonals, etc). Scale Factor: If two polygons are similar, then the ratio of the lengths of two corresponding sides is called the scale factor.

1. The two triangles are similar, find the missing angles 120° 50°

2. Triangle ABC ~ Triangle DEF, find x and y. A B C D E F x 18 3 y 10 2

3.Two similar rectangles have sides in the ratio of 3 : 7. If the smaller rectangle has a perimeter of 50m, find the perimeter of the larger rectangle.

4. Are these polygons similar (the sum of the angles in a pentagon is 540◦)? ◦ ◦ 100◦

Determine whether the polygons are similar. If so, write the similarity ratio and a similarity statement and find the scale factor from quad ABCD to quad EFGH.