We need to know about protractor, which is a semi-circular tool for measuring angles. There are many scales on the protractor, which can help us to determine the angle. Next, we can measure the angle according to the following steps: aim the center point of the protractor at the vertex of the angle. Align one side of the protractor with one side of the corner.
When the other side of the protractor is aligned with the other side of the angle, the angle is as much as the scale. It should be noted that when measuring the angle, the protractor should remain stable and not shake, so as not to affect the accuracy of the measurement results. At the same time, we should also pay attention to the accuracy of the reading, see the scale clearly and don't read it wrong.
Matters needing attention in reading protractor:
1. Determine the scale range of protractor: protractor usually has two scales, inner and outer, which correspond to different degree ranges, so choose the appropriate scale range according to the measured angle.
2. Determine the position of the scale line: find the scale lines corresponding to the two sides of the measured angle on the protractor, and the scale between these two scale lines is the degree of the measured angle.
3. Pay attention to the calibration accuracy: the calibration accuracy on the protractor may be different, so it is necessary to estimate or read the nearest integer degree according to the specific situation.
4. The line of sight should be parallel to the scale line: when reading the scale number on the protractor, our line of sight should be parallel to the scale line, so as to avoid the reading error caused by the tilt of the line of sight.
5. Estimate the next digit of the minimum division value: When reading the scale number on the protractor, we need to estimate it according to the minimum division value of the protractor. For example, if the minimum scale value of protractor is 1, then we need to estimate it to 0. 1. This can improve the accuracy of measurement.
6. Ensure that the protractor is placed stably: when using the protractor, it should be placed stably to avoid shaking or tilting, so as not to affect the accuracy of the measurement results.
7. Pay attention to the distinction between internal and external scales: protractors usually have internal and external scales, and it is necessary to choose the appropriate scale according to the size and direction of the measured angle. At the same time, when reading the ruler, we should also pay attention to distinguish between the internal and external rulers to avoid mistakes.