Download leg leg hypotenuse

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A triangle is a 3sided polygon.
Every triangle has
three sides and
leg
three angles, which
when added
together equal
180°.
hypotenuse
leg
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1
B
Triangles consist of 3 things :
1) Vertices
A , B, C
A
C
Many Ways to Name a Triangle
△ABC
△ACB
△BAC
△BCA
△CAB
△CBA
2) Sides
AB , BC , AC
3) Angles
∠A , ∠ B , ∠ C
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Congruent triangles
are triangles whose
corresponding
angles and sides
are congruent.
They are exactly the
same size and
shape.
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2
Sides opposite congruent angles
are congruent.
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Angles opposite congruent
sides are congruent.
8
8
6
6
11
8
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3
In this slide show you will learn
that we identify triangles by:
their angles
and the length of their sides.
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If an angle is less than 90º it is an
Acute Angle. If it is greater than 90º it
is an Obtuse Angle. If you have an
angle that is 90º exactly it is called a
Right Angle.
Acute
Obtuse
Right
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The next three triangles
are classified by their
angles
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An acute triangle has three
acute angles. All three angles
are less than 90º
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An obtuse triangle has only one
obtuse angle. One angle is
greater than 90º
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A right triangle has exactly one right
angle. The right angle measures 90º
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In a right triangle, the side
opposite the right angle is
called the hypotenuse.
A triangle with
a 90º angle is
called a right
triangle.
The other
two sides are
called legs.
The small square
indicates a 90º
angle.
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The next three triangles
are classified by the
length of their sides.
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An equilateral triangle has three
congruent sides and three
congruent angles. All three
sides have the same length.
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An equiangular
triangle is also
know as an
equilateral triangle.
It is a triangle
which has three
equal angles.
60°
60°
60°
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An isosceles triangle has at least
two equal (congruent) sides.
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A scalene triangle has three
unequal sides. No sides are
congruent.
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9
Name the following figures.
octagon
acute
triangle
right
triangle
WORD BANK obtuse angle straight angle right angle
obtuse triangle acute triangle octagon
obtuse
triangle
acute angle
right triangle
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Name the following figures.
•
obtuse
angle
right
angle
acute
angle
WORD BANK obtuse angle straight angle right angle
obtuse triangle acute triangle octagon
straight
angle
acute angle
right triangle
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10
Name the following figures.
trapezoid
rectangle
WORD BANK scalene triangle
equilateral triangle
square
rectangle
scalene
triangle
isosceles
triangle
isosceles triangle
trapezoid
rhombus
regular hexagon
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Name the following figures.
equilateral
triangle
square
WORD BANK scalene triangle
equilateral triangle
square
rectangle
rhombus
regular
hexagon
isosceles triangle
trapezoid
rhombus
regular hexagon
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Every triangle has a total angle sum of 180º
b
c
a
m∠a + m∠b + m∠c = 180°
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Every triangle has a total angle sum of 180º
m∠x + 85° + 65° = 180°
Solve for x.
x + 150 = 180
85°
x
−150 − 150
65°
x = 30
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12
1) If a triangle has Answer:
three unequal sides
a) Scalene
it is a ______
triangle.
a) Scalene
b) Obtuse
c) Isosceles
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2) A triangle which Answer:
has three equal
b) Equilateral
angles is a ______
and
triangle.
a) Acute
c) Equiangular
b) Equilateral
c) Equiangular
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3) A triangle with
Answer:
(at least) two equal
b) Isosceles
sides is a ______
triangle.
a) Scalene
b) Isosceles
c) Congruent
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4) Two triangles
that are equal are
called ______
triangles
a) Acute
b) Obtuse
c) Congruent
Answer:
c) Congruent
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5) A triangle with all
three sides of equal
length is a ______
triangle.
a) Equilateral
b) Right
c) Equiangular
Answer:
a) Equilateral
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6) A triangle with an Answer:
angle of 90° is a
b) Right
______ triangle.
a) Acute
b) Right
c) Congruent
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7) A triangle in which Answer:
all three angles are
b) Acute
less than 90° is a
______ triangle.
a) Right
b) Acute
c) Scalene
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8) A triangle in which Answer:
one of the angles is
a) Obtuse
greater than 90° is a
______ triangle.
a) Obtuse
b) Isosceles
c) Acute
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9) What is the
hypotenuse of a right
triangle?
a) The smallest angle.
b) The side opposite
the right angle.
c) The right angle.
Answer:
b) The side
opposite the
right angle.
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Name each triangle below by BOTH names.
1)
2)
6
6
3
10
Obtuse Isosceles
5
4
Right Scalene
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Name each triangle below by BOTH names.
3)
4)
3
7
9
Acute Equilateral
Obtuse Scalene
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Name each triangle below by BOTH names.
5) 2
6)
4
7
Acute Scalene
5
3
7
Right Scalene
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Name each triangle below by BOTH names.
7)
8)
5
5
Acute Isosceles
Right
Isosceles
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The End
Take out your study guide
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#1
These types of triangles are
classified by their angles.
Right Triangle
A triangle with one right angle. (90°)
Acute Triangle
60
60
60
A triangle with three acute angles.
(3 angles less than 90°)
Obtuse Triangle
115
A triangle with one obtuse angle.
(1 angle greater than 90°)
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#2
These triangles are classified by their sides.
Equilateral Triangle
All three sides are equal or congruent.
Isosceles Triangle
A triangle with 2 equal sides.
Scalene Triangle
A triangle with no equal sides.
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20
#3
Find The Missing Angles
The total sum of the angles inside a triangle is 180°
1.
2.
?30°
90°
? 45°
90°
60°
3.
4.
85°
31°
45°?
42°
64° ?
?50° 88°
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