Download L5 Triangles

Triangles
Vocabulary:
Triangle - A three-sided shape made up by the intersection of 3 lines.
Classifying Triangles
By Angle:
Acute Triangles- all angles are less than 90°.
Obtuse Triangles- has one angle greater than 90° and two angles less than 90°.
Right Triangles- has one angle exactly 90°.
By Side:
Equilateral Triangles- all sides are congruent.
**Note- All angles are ALSO congruent.**
60
°
60
°
Isosceles Triangles- TWO sides are congruent.
**Note- 2 angles will also be congruent.**
Scalene Triangles- has NO congruent sides.
60
°
Perimeter of a Triangle: Add all of the sides together.
Area of a Triangle:
1
___
2
bh
4
ft
3
m
7
in
2
ft
7
in
1
m
Measuring Triangles Using Protractors
ALL OF THE ANGLES OF A
TRIANGLE ADD UP TO
180°!!!!
Creating Triangles Based on Given Information
Draw and label a triangle where
B=60°, and
C=90°.
A=30°,
Creating Triangles Based on Given Information
Draw and label a triangle where
B=75°, and
C=90°.
A=15°,
Creating Triangles Based on Given Information
Draw and label a triangle where
B=60°, and
C=60°.
A=60°,
Determining Triangles
If:
A+B > C
B+C > A
and
A+C > B
Then you have a triangle.
If any of those are untrue, than it will NOT make a
triangle.
Will the follow create a triangle:
Side A=
3 in.
Side A=
10 in.
3 in. B=
C=
4C=
in.
Side A=
B=
3 in.
2 in.
B=
2 cm
C=
3 cm
Side A=
4 cm
B=
C=
5 yds
3 yds
2 yds
Review:
HW:
Vertical Angles are equal when made by straight intersecting lines.
Triangles should be labeled by their sides AND their angles.
ALL TRIANGLES ADD UP TO 180°!!!
Using Vertical Angles and Creating Triangles
Worksheet