Download 6.3 Use Similar Polygons

6.3 Use Similar Polygons
Similar (῀) Polygons
• Corresponding angles are congruent
• Corresponding sides are in proportion
Scale factor
Ratio of the lengths of two corresponding
lengths of matching sides.
Always reduces
A
12
Q
10
D
B
6
x
16
C
4
T
8
• Find scale factor of ABCD to QRST
• Find x
R
S
Perimeters of similar figures
• Ratio of the perimeters is equal to the ratio of
the corresponding side lengths
6.4 Prove Triangles Similar by AA
• AA similarity postulate – if two angles of one
triangle are congruent to two angles of
another triangle, then the triangles are similar.
See pg. 382
Given: AB // DE
A
Prove: triangle ABC is similar to
triangle EDC
D
C
B
E