Transcript Lesson 4-2B PowerPoint

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Lesson 4-1 Classifying Triangles
Lesson 4-2 Angles of Triangles
Lesson 4-3 Congruent Triangles
Lesson 4-4 Proving Congruence–SSS, SAS
Lesson 4-5 Proving Congruence–ASA, AAS
Lesson 4-6 Isosceles Triangles
Lesson 4-7 Triangles and Coordinate Proof
Example 2 Exterior Angles
Example 3 Right Angles
OBJECTIVE: To apply the Exterior Angle Theorem
(2.9.8D) (M8.C.1.1)
Theorem 4.2 – Third Angle Theorem: If 2
angles of one triangle are congruent to two
angles of a second triangle, then the third
angles of the triangles are congruent
Theorem 4.2 – Exterior Angle Theorem: The
measures of an exterior angle of a triangle is
equal to the sum of the measures of the two
remote interior angles.
Find the measure of each numbered angle in the figure.
Exterior Angle Theorem
Simplify.
If 2 s form a linear pair, they
are supplementary.
Substitution
Subtract 70 from each side.
Exterior Angle Theorem
Substitution
Subtract 64 from each side.
If 2 s form a linear pair,
they are supplementary.
Substitution
Simplify.
Subtract 78 from each side.
Angle Sum Theorem
Substitution
Simplify.
Subtract 143 from each side.
Answer:
Find the measure of each numbered angle in the figure.
Answer:
GARDENING The flower bed shown is in the shape of
a right triangle. Find
if
is 20.
Corollary 4.1
Substitution
Subtract 20 from each side.
Answer:
The piece of quilt fabric is in the shape of a
right triangle. Find
if
is 32.
Answer:
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