Download Congruent Triangles

Congruent Triangles
Warm up
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Draw a triangle with a straightedge
Label the vertices A, B, and C
How many angles are there in the triangle?
Name the angles.
How many sides are there?
Name the sides.
Tools needed
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Ruler
Compass
Protractor
Scissor
paper
Group Activity
• Compare the triangle drawn with your
neighbour’s.
• Are the two triangles exactly the same.
Group Activity
• Draw a right triangle with leg lengths of 3 and
4 units on the graph paper.
• Cut it out.
• Compare with your partner’s triangle.
• Are they the same size and shape?
• Can you put the two triangles together one on
top of the other?
Definition of congruent triangles
• Two triangles are congruent if and only if their
corresponding angles and corresponding sides
are congruent
Congruent Triangles
• Table 1: Draw a triangle with side lengths of 3,
4 and 6 cm long.
• Table 2: Draw a triangle side lengths of 6 and 4
cm and the included angle of 30o.
• Table 3: Draw a triangle with 2 angles of 55o
and and 50o and the included side of 7 cm.
• Table 4: Draw a triangle with 2 angles of 55o
and and 50o and the nonincluded side of 7 cm.
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Cut it out.
Compare with your partner’s triangle.
Are they the same size and shape?
Can you put the two triangles together one on
top of the other?
• Are the corresponding angles congruent?
• Are the corresponding sides congruent?
• Are the triangles congruent?
Shortcut to prove triangles congruent.
• Name the 5 methods to prove triangle
congruent.
summary
WORDS
Def of ∆

SSS
SAS
ASA
AAS
HL
All the
corr.
angles
and corr.
sides are
congruent
3 sides of
1 triangle
are
congruent
to 3 sides
of another
triangle
2 sides and
the
included
angle of 1
triangle
are
congruent
to 2 sides
and the
included
angle of
another
triangle
2 angles
and the
included
side of 1
triangle are
congruent
to 2 angles
and the
included
side of
another
triangle
2 angles
and a
noninclude
d side of 1
triangle are
congruent
to 2 angles
and a
noninclude
d side of
another
triangle
The
hypotenuse
and a leg of
a right
triangle are
congruent
to
the
hypotenuse
and a leg of
another
right
triangle
PICTURES
.
Homework
• Page 288
• # 1 – 9, 16, 17