- Angles, Lines, and Polygons
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- Measuring an angle with the protractor
- Acute, obtuse, and right angles
- Naming segments, rays, and lines
- Identifying parallel and perpendicular lines
- Acute, obtuse, and right triangles
- Classifying scalene, isosceles, and equilateral triangles by side lengths or angles
- Finding an angle measure of a triangle given two angles
- Naming polygons
- Drawing and identifying a polygon in the coordinate plane
Measuring an angle with the protractor
An angle is formed when two lines intersect in a point. The rays emerging from the common point called vertex are the arms of the angle.
The magnitude of how big or small an angle is given by its measure in degrees or some other units
We place the midpoint of the protractor on the vertex of the angle.
Then we line up one side of the angle with the zero line of the protractor.
We then read the degrees where the other side crosses the number scale.
Measure the following angle using a protractor.
Solution
Step 1:
Line up one ray with 0°. Read the angle measurement where the other ray crosses the protractor.
Step 2:
Reading from the protractor, the given angle measures 17°.
Measure the following angle using a protractor.
Solution
Step 1:
Line up one ray with 0°. Read the angle measurement where the other ray crosses the protractor.
Step 2:
Reading from the protractor, the given angle measures 132°.
