Answer:
a) corresponding angles of similar polygons are congruent
b) corresponding sides of similar polygons are proportional
c) a triangle is a polygon
Step-by-step explanation:
By <em>definition</em>, similar polygons have congruent corresponding angles and proportional corresponding sides.
A triangle is a polygon, so two triangles will be similar if they have congruent corresponding angles and proportional corresponding sides.
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For an n-sided polygon, one only needs to show the conditions are met for n-1 angles and sides. Those will determine the measures of the final angle/side.