Download Yr 2 w-up 9/21 – copy the pictures

Year 2 warm-up
1. Determine if it is possible to draw the triangle with the given sides,
if no state why
3 cm, 6, cm, and 11 cm
2. Arrange the angles from least to greatest.
b
14
a
19
c
21
3. Find the missing value.
30°
x
110°
Warm-Up Answers
1. No, because 3 + 6 < 11
2. c, a, b
3. x = 80°
4.4 Triangle Congruence
shortcuts
Strand 4 Concept 1 P.O. 8
Objective:
SWBAT Prove similarity and congruence of triangles.
What can we compare in two triangles to
determine if they are congruent?
3 sides (s) and 3_______
angles (a)
________
But wait!
There are shortcuts…what if we could
compare just 3 parts of a triangle?
We are going to talk about the following
shortcuts and see which ones work for
us:
SSS, SAS, ASA, and HL
Let’s take a look at the 1st shortcut…
1:
SSS congruence conjecture:
If three sides in one triangle are
congruent to three sides of another
triangle, then the triangles are
congruent.
1. SSS Conjecture Investigation:
Is ABD  CBD
Given: D is the midpoint of AC
(Mark what you know on the triangle)
B
S
A
S
S
S
D
C
S
Yes they are congruent
because of SSS!
Next to bat is…….
2:
SAS Congruence Conjecture:
If two sides and the included angle in
one triangle are congruent to two sides
and the included angle of another then
the triangles are congruent.
2. SAS Conjecture Investigation:
Is ABC  DFE ?
Given <B 
<F
E
Mark what you know!
A
S
S
D
F
S
A
C
B
S
Included angle (between
the two sides given)
Yes they are congruent
because of SAS!
And now presenting…
3:
ASA Congruence
Conjecture:
If two angles and the included side
of one triangle are congruent to two
angles and the included side of
another triangle, then the triangles are
congruent.
3. ASA Conjecture Investigation:
Is BCD  EFG?
 B  E and  D  G
BD  EG
Mark what you know!
Yes they are congruent
because of ASA
C
F
B
A
A
S
D
E
A
A
S
G
Last congruence shortcut…
• HL – Hypotenuse-leg
If the hypotenuse and one leg of a right
triangle is congruent to the hypotenuse
and one leg of another right triangle, then
the triangles are congruent.
Hypotenuse (longest side,
across from the right angle)
leg
leg
Summary…
Draw a sketch of each of the 4 triangle
congruencies that show 2 triangles are
congruent to one another (This means you
should have a total of 8 triangles drawn all with
proper markings and labels!)
Classwork:
Congruent Triangles Worksheet
Homework: 4.4 pg 222-223
#1-6, 9-14
(If the triangles are not congruent write
“can not be determined”)