Angles Review and Triangles

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Angles Review and Triangles
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What do we know about angles?

• Three types
• Acute
• Right
• Obtuse

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An acute angles measurement is less
than 90 degrees.
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A right angle measures exactly 90 degrees.
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An obtuse angles measurement is greater than 90
degrees but less than 180 degrees.
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What type of angle is this?

• Acute
• Obtuse

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Incorrect
An acute angle is less than 90 degrees. Try
Again!
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Correct
That angle measures over 90 degrees making it
obtuse!
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Using Angles to classify Triangles!
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A right triangle has exactly
one right angle.
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An acute triangle has three acute angles.
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Finally, an obtuse triangle has one obtuse angle.
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Finally, an equiangular triangle has all angles
of 60 degrees.
600
600
600
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According to angles how would you classify this
triangle?

• Acute Triangle
• Right Triangle

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Incorrect
A right triangle has at least one right angle.
Like the one below. Try Again!
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Correct!
An acute triangle has all acute angles, which are
less than 90 degrees. Great Job!
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Classifying Triangles by their Sides!
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A scalene triangle has no congruent sides.
Congruent means equal.
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An isosceles triangle has two congruent sides.
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An equilateral triangle has all congruent sides
and angles.
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NOw Lets review!
You can classify this triangle two ways which are
they??

• Scalene and Obtuse
• Isosceles and Acute
• Equilateral and Right

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That is Incorrect
A triangle that is obtuse has an angle that
measures over 90 degrees. Also a scalene triangle
has no congruent sides, this triangle had two
sides which were congruent. Try again!
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That is Incorrect
An equilateral triangle has all equal sides and
equal angles. This triangle only had two
congruent sides. Try again!
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Correct!
An isosceles triangle has two congruent sides. An
acute triangle is made up of only acute angles.
Good Job!
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?? One more question ??
A triangle can be a right triangle and a scalene
triangle
True False
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That is incorrect
A right triangle does not always have a set of
congruent sides, rethink your answer and try
again!
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That is Correct!
A triangle can have a right angle and still have
no congruent sides.
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Classifying Triangles by Their Angles
All angles will always be 600.
600
Equiangular Triangle
Will always be an equilateral triangle too.
600
600
60
All 3 angles measure less than 90 degrees.
Acute Triangles
80
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Right Triangle
One angle measures 90 degrees and the other
two angles are acute.
One angle that measures more than 90 degrees and
the other two are acute.
Obtuse Triangle
30
20
130
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Classifying Triangles by Their Sides
EQUILATERAL
3 congruent sides
All angles will always equal 600 .
ISOSCELES
2 congruent sides
Angles that are not formed by the equal sides are
also equal
SCALENE
No congruent sides
No equal angles
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Great Job Class!
Now you know the basics of angles and how to
classify triangles!