Download A postulate for similar triangles

7-4
Exploration
•
Draw any two segments… AB and A’B’. Try not to make them the same size.
•
Draw any angle at A and a congruent angle at A’.
•
Draw any angle at B and a congruent angle at B’
•
Close off the triangles and label C and C’ appropriately.
•
Measure all three sides of each triangle.
•
Find the following ratios and make a conclusion:
AB
A' B'
AC
A'C '
BC
B'C'
AA Similarity Postulate
• If two angles of one triangle are congruent to two angles of
another triangle, then the triangles are similar.
• **This is HUGE! This means we don’t have to check the ratio of
the side lengths every time. As long as two angles are congruent,
we automatically know that the triangles are similar.