Download Types of Angles

Mathematics: Geometry
Grade 5
Types of Angles
Picture
Name of Angle
Description
Acute Angle
I am the smallest type of
angle and I am very CUTE. I
am always less than 90º.
Right Angle
I am perfectly straight and
always RIGHT. I am exactly
90º.
Obtuse Angle
I am a lot more relaxed than
the Right Angle, and therefore
OBviously more than 90º,
but less than 180º.
Straight line
I like to walk on the
STRAIGHT and narrow line, I
never go anywhere but 180º.
Reflex Angle
I am so FLEXible that I can
bend all the way past 180º.
Revolution
I don’t like to be like the rest,
I want a REVOLUTION and
we can all dance in a circle. I
am exactly 360º.
Charlie says: “Always
start on the horizontal
line, then walk toward
the angled line.”
45º
129º
180º
135º
360º
Mathematics: Geometry
Grade 5
Identifying Angles
Can you identify the indicated angles in these pictures? Give
the name and description of each angle.
1
_______________
________________
2
_______________
________________
________________
3
________________
________________
4
1
_____________
________________
_____________
________________
________________
2
________________
See if you can find all these angles in each of the pictures below:
Draw the Obtuse angles in red, the Right angles in blue, the Acute angles in
black and the Reflex angles in Green.
Make sure that you find ALL the angles in each picture!
2
Mathematics: Geometry
Grade 5
Measuring and Drawing Angles
When measuring angles, we use a protractor. A protractor has an inner scale
and an outer scale. The way in which the angle faces, will indicate to you if
you should use the inner or outer scale to measure or draw the angle.
Acute angle, facing left, will
be measured or drawn using
the outer scale (0º— 90º)
Acute angle, facing right, will
be measured or drawn using
the inner scale (0º— 90º)
Obtuse angles,
facing right, will
be measured with
the inner scale
(90º—180º)
Obtuse angles,
facing left, will be
measured with the
outer scale
(90º—180º)
A
STEPS to follow for measuring angles:
Step 1: Make sure which angle you should be measuring.
ABC, means you have to measure angle B.
Step 2: Extend any lines with your ruler to ensure
that you can see the line all the way past your
protractor.
Step 3: Make a dot where the two lines meet, big
enough for you to see through the protractor. This
will help you put the protractor exactly in the
middle.
Step 4: Decide if you will measure with the inner
or outer scale, using the explanation above.
B
C
Step 5: Make sure your protractor is exactly straight on the bottom line and that your dot
is exactly on the perpendicular line facing towards 90º.
Step 6: Measure the angle—in this example, the angle measures 55º.
STEPS to follow for drawing perfect angles:
Step 1: Always start with a dot where you would like to draw your angle, then draw a
straight horizontal line from where you will begin.
Step 2: Measure the angle using your protractor. Remember to follow the instructions
carefully. Is it facing right or left? Will it be an Acute angle or an Obtuse angle? The
answer to these questions will tell you if you will be using the inner or outer scale.
Step 3: Make a visible mark at exactly the correct degrees. Remember to make sure that
your protractor does not move while you are measuring.
Step 4: Connect your dot with that mark, using a ruler.
Step 5: Draw a semi-circle or a square (90º) to indicate the angle you have measured
and write in the degrees of that angle.
3
Mathematics: Geometry
Grade 5
Measuring and Drawing Angles
Measure the following angles, using your protractor:
HINT: Turn the page, until the angle you have to measure is horizontal.
C
X
Y
D
E
Z
Type of angle:
Type of angle:
Size of
Size of
CDE:
XYZ:
R
G
E
S
T
F
Type of angle:
Type of angle:
Size of
Size of
EFG:
RST:
K
17
H
L
70
I
93
M
G
Type of angle:
Type of angle:
Size of
Size of
GHI:
4
KLM:
Mathematics: Geometry
Grade 5
Measuring and Drawing Angles
Draw the following angles in the space provided:
ABC, 76º, left facing
DEF, 162º, left facing
XYZ, 29º, right facing
MNO, 83º, right facing
JKL, 146º, right facing
GHI, 101º, left facing
5
Mathematics: Geometry
Grade 5
Identifying Angles—Memo
Can you identify the indicated angles in these pictures? Give
the name and description of each angle.
1
Obtuse angle, bigger
1. Right angle, 90º
2
than 90º, smaller than
2. Obtuse angle, > 90º,<180º
180º
3
3. Reflex angle, > 180º
4. Acute angle, < 90º
4
1
Obtuse angle,
1. Reflex angle, > 180º
> 90º, < 180º
2. Acute angle, < 90º
2
See if you can find all these angles in each of the pictures below:
Draw the Obtuse angles in red, the Right angles in blue, the Acute angles in
black and the Reflex angles in Purple.
Make sure that you find ALL the angles in each picture!
Remember that angles
forms only where STRAIGHT
lines meet.
6
Mathematics: Geometry
Grade 5
Measuring and Drawing Angles—Memo
Measure the following angles, using your protractor:
HINT: Turn the page, until the angle you have to measure is horizontal
43.5
C
X
Y
E
49.5
84
D
92.9
43.6
Z46.5
Type of angle: Obtuse
Type of angle: Acute
Size of
Size of
43
.5
CDE: 92º
R
46
.5
G
XYZ: 84º
15
.8
E
14
8
90
S
1T
6.2
F
Type of angle: Right
Type of angle: Obtuse
Size of
Size of
EFG: 90º
2K6
.2
17
H
93
M
25
.8
L
70
I
RST: 148º
12
8
G
Type of angle: Acute
Type of angle: Obtuse
Size of
Size of
GHI: 17º
7
KLM: 128º
Mathematics: Geometry
Grade 5
Measuring and Drawing Angles—Memo
Draw the following angles in the space provided:
ABC, 76º, left facing
DEF, 162º, left facing
A
68.8
F
76º
35.2
DA
B
76
E
C
XYZ, 29º, right facing
MNO, 83º, right facing
M
X
Y
29º
Z
N
O
JKL, 146º, right facing
GHI, 101º, left facing
I
J
L
101º
K
G
8
H