Warmup

Homework problems

16 (p.160, from last time)

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Proof

1	seg AC ≅ seg BE	given
2	∠AEB and ∠BCA are right angles	def. ⊥
3	seg AB ≅ seg AB	reflexive prop
4	△AEB ≅ △BCA	HL (1,2,3)
5	∠DAB ≅ ∠DBA	CPCTC (4)
6	seg AD ≅ seg BD	angle-side theorem (5)
7	seg AE ≅ seg BC	CPCTC (4)
8	seg ED ≅ seg BD	subtraction property (6,7)
9	seg DE ≅ seg EC	given
10	△DEC is equilateral	def. equilateral (8,9)

Review #3 (p.162)

Remember, because two points determine a line or segment or ray, you can add these to figures if you have the two points.

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Proof

1	Draw seg OF and seg OH	two points determine a segment
2	seg OG ⊥ seg FH	given
3	∠FGO and ∠HGO are right angles	def. ⊥
4	seg OF ≅ seg OH	all radii are congruent
5	seg OG ≅ seg OG	reflexive prop.
6	△FGO ≅ △HGO	HL (3,4,5)
7	seg FG ≅ seg GH	CPCTC (6)

#14 (p. 164)

Sorry; trick question. This cannot be proved. Check the toy: Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now) to see.