Download If you want to say that two triangles are similar, then you must show

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Name: ________________________________________
If you want to say that two triangles are similar, then you must show or demonstrate that all
corresponding angles are congruent and all corresponding sides are proportional. Proportional means
that all ratios of the corresponding sides are equal. That means:
G
A E
B F
C
A
B
C G
AB BC CA


EF FG GE
E
F
If you show all the angles are congruent and all the sides are proportional, then you can say that
ABC EFG .
Do we really need to show all that above to say two triangles are proportional?
1. Make another smaller triangle using only the bottom angles.
2. Are all the corresponding angles congruent?
3. Measure the sides of each triangle and divided the larger corresponding side with the smaller.
4. Are all the calculations above about equal with some error?
5. How many corresponding congruent angles does one need to say triangles are similar?
Can we find a relationship with sides?
Using the triangle below, make another one using spaghetti noodles where all the sides are half as
long.
1. Does the original triangles’ and the noodle triangles’ corresponding angles have the same measure?
2. Are your triangles similar?