ANGLES
An ANGLE is formed when two straight lines meet at a
point (or vertex).
(1) AP and AB are the 2 straight lines
(2) Vertex or point
P (upper cap)
(3) An
angle APB
or angle x (lower cap)
Practice
The learner to use 2 pencils to form an angle,
and to state
(a) the two straight lines,
(b) the point and
(c) the angle
What
is a Point?
-
A precise location or place, usually represented by a dot.
-
It has no size, no matter how far you zoomed in(no width)
-
Is a place, not a thing -> no dimensions
IDENTIFYING AND COMPARING
ANGLES
Example
What are the types of angles?
Obtuse right-angle acute acute
Example
(1) What are the types of angles between: A and B, B and C, C and D and D and E?
<Acute>
(2) Which two fingers when stretch can form an obtuse angle?
<Finger D and E>
<Obtuse (form O from finger D&E), DE can be extended to form an obtuse angle>
Example
Count the number of obtuse angle in the diagram.
Step1: What is an obtuse angle? <more than 90o>
Step2: Circle obtuse angles.
Total number of obtuse angles = 4
NAMING ANGLES
Examples
Name the angles
An Angle is a measure
of turn. It is measured in degree or the symbol °.
<Ask the learner what are these measured in a. Distance
b. Weight c. time >
USING THE PROTACTOR
Angles are measured using a protractor.
Here's how to use a protractor to measure an angle:
- Line up the protractor so the 'cross hair' is exactly on the angle.
- Line up one of the lines with the 0 line on the protractor.
- The line is between 30 and 40, the angle must be thirty something
degrees.
- Count the small degrees up from 30. In the diagram, the angle is
35°.
~~~~ END ~~~~ :)
