Let Us Learn About Measuring angles.
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An angle is an amount of rotation of a half-line (or ray) in a plane about its end point from an initial position to a terminal position. The important terms are: Measurement of angle, Positive and Negative angles, Lines at right angles, Quadrants, Angle in standard position.
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To measure an angle we shall use two kinds of units, the degree unit and the radian unit.
A degree (Sexagesimal system) is defined to be an angle formed by half-line (or a ray) rotated about its end point (1/360) of a complete revolution.
Types of Angles: Acute angle, Obtuse angle, Right angle, Reflex angle, A straight angle.
Steps to draw an angle with a protractor,
A straight line is drawn (i.e. an arm of the angle).
A dot is marked at the end of the arm. This marked dot represents the vertex of the angle.
To construct your angle you will use the direction of the arrow points at the zero
Place the centre of the protractor at the vertex marked dot and the baseline of the protractor along the arm of the angle.
Find the required angle on the outer scale and then mark a small dot at the edge of the protractor.
The small dots are joined to the vertex with a ruler to form the second arm of the angle.
Label the angle.
measuring angles lessons and activities will help you to understand better. Our next topic will be on Three systems of Measuring Angles
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