Download Geometry 2.5 ‐ Proving Angles Congruent A. Recall: • Theorem ‐ a

Geometry
2.5 ‐ Proving Angles Congruent
A. Recall:
Theorem ‐ a statement or theory that was proven to be true. The •
process through which a theory is proven to be a theorem is called a proof
Postulate ‐ a statement that is accepted as true but hasn’t been proven •
true, thus hasn’t become a theorem. B.
•
Vertical Angles Theorem
Vertical angles are congruent. 1
2
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1
(2x ‐ 38)0
(2x ‐ 10)0
(4x ‐ 40)0
(x + 22)0
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2
B
(x + 81)0
C
E
C
(y)0
(5x + 17)
0
(2x)0
D
A
(y + x)0
E
B
(y ‐ x)0
D
A
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D.
Congruent Complements Theorems
Theorem 2.3 ‐ if two angles are complements of the same angle, or of congruent angles, then the two angles are congruent
Theorem 2.4 ‐ all right angles are congruent
Theorem 2.5 ‐ if two angles are congruent and supplementary, then each is a right angle. Sep 17­11:05 AM
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1
3
2
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1
2
3
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2.5 HW p. 112 #s 1 ‐ 13 all
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