Chapter 19: Geometrical Constructionss Exercise 19.4
Question: 1
Construct the following angles with the help of protractor:
45°, 67°, 38°, 110°, 179°, 98°, 84°.
Solution:
We draw a ray OA.
We place the protractor on OA such that its center coincides with the point 0 and the diameter of the protractor coincides with OA.
We mark a point B against the mark of 45° on the protractor.
We remove the protractor and draw OB. ∠AOB is the required angle of 45°.
Similarly, we draw the angles 67°, 38°, 110°, 179°, 98° and 84°.
Question: 2
Draw two rays PQ and RS as shown in figure. Using the protractor, construct angles of 15° and 138° with one arm PQ and RS respectively.
Solution:
(i) Draw a ray PQ as given in the question.
Place the protractor on the ray PQ such that its center coincides with the point P and the diameter of the protractor coincides with PQ.
Mark a point B against the mark of 15° on the protractor.
Remove the protractor and draw PB. ∠QPB is the required angle of 15°.
(ii) Draw a ray RS as given in the question.
Place the protractor on ray RS such that its centre coincides with the point R and diameter of the protractor coincides with RS.
Mark a point T against the mark of 138° on the protractor.
Remove the protractor and draw RJ.
∠SRTIIs the required angle of 138°.