Mada za sehemu hiiGeometryMada 15
- Measuring angles
- Drawing angles by using a protractor
- Angles in plane figures
- The parallelogram
- The Trapezium
- Circumference of a circle
- Area of Plane Figure
- Area of Trapezium
- Area of a circle
- Areas of three-dimensional figures
- Surface area of a cylinder
- Volumes of three-dimensional figures
- Volume of a cylinder
- Coordinate geometry
- Drawing plane figures using coordinates of points
An angle is the amount of space between two intersecting lines. Angles are measured by using a protractor. The protractor takes measurements in degrees which start from 0 to 180 degrees, that is from 0° to 180°.
The protractor has inner and outer scales. An angle can be measured from any side of the protractor. A decision to use either the inner or the outer scale depends on the position of the reference line. The angles are measured from 0° to 180° on the scale where the reference line points.
Measure the angle in the following figure:
- Put the protractor on the figure so that the line from 0° to 180° of the protractor lies on BC.
- Make sure that the angle formed by line from 0° to 180° and the vertical line of the protractor lies exactly on .
- The line AB will show the required degree measure of the angle.
- Read and record the degree which coincides with AB on the inner scale of a protractor.
- The degree on the scale where AB extends is the size of the angle.
- Therefore, angle ABC is 45°.
- Put the protractor on the figure in such a way that line from 0° to 180° lies on AC. Make sure that the vertical line and horizontal line from 0° to 180° of the protractor meet at point O, that is, the point where OC and OB meet.
- Read the degree which is on from the inner scale of the protractor. The number on the scale where OB extends is the size of .
- Therefore, is 140°.
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