Construction of an Angle using a Protractor

We will learn how to construction of an angle using a protractor.

1. Let us draw an angle whose measure is 60°. Use a ruler to draw YZ. 

Now, place the protractor over YZ such that the baseline of the protractor coincides with YZ and midpoint of the baseline coincides with point Y.

Mark a point X where you find 60 on the protractor. Now, join X and Y with the help of a ruler. We ∠XYZ = 60°.

2. Let us draw an angle EFG measuring 120°. Draw a ray EF. Place the protractor over EF such that the baseline of the protractor coincides with EF and the midpoint of the baseline coincides with point F. Read markings on the outer semicircle of the protractor and mark point G on 120°.

Join F and G with the help of a ruler. We have ∠EFG = 120°.

3. Draw an angle PQR = 45°

Step I: Draw a ray QR as shown in the figure.

Step II: Keep the centre of the protractor at Q.

Step III: Adjust the base line of the protractor along $\overrightarrow{QR}$.

Step IV: Find the ‘0’ on the scale where the ray crosses the protractor.

Step V: Follow along that scale and mark a point ‘P’ against the 45° mark.

Step VI: Remove the protractor and draw a ray from the vertex Q to the point P.

Step VII: ∠PQR = 45° is the required angle.

3. Draw an angle XYZ = 90°

Step I: Draw a ray YZ as shown in the figure.

Step II: Keep the centre of the protractor at the vertex Y.

Step III: Adjust the base line of the protractor along $\overrightarrow{YZ}$.

Step IV: Find the ‘0’ on the scale where the ray crosses the protractor.

Step V: Follow along that scale and mark a point ‘X’ against the 90° mark.

Step VI: Remove the protractor and draw a ray from the vertex Y to the point X.

Step VII: ∠XYZ = 90° is the required angle.

Construction of an Angle of given Measure Using Protractor and Straight-edge:

Let ∠PQR = 50° be given. Let us follow the Working Rules given below to draw this angle using the protractor and straight-edge.

Step I: Draw $\overline{QR}$ of any length.

Step II: Place the centre of a protractor at Q and zero-edge along $\overline{QR}$.

Step III: Start with zero near R and mark point Pat given angle, here 50°.

Step IV: Join PQ. Now, ∠PQR = 50° is the required angle.

5th Grade Math Problems 

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