Question 1: of exercise 11.2 page 195 of Maths

Construct a triangle ABC in which BC = 7 cm, âˆB = 75 and AB + AC = 13 cm.

As explained in this question (Step III: Join DC and make an angle DCY equal to âˆBDC.)

Step 3 is not clear. Explain how to make an angle equal to another angle without protractor.

In step 3, it says, join DC and make an ∠DCY = ∠BDC.

Now, as ∠DCY = ∠BDC, we can say, AC = AD (Sides opposite to equal angles are equal).

Now, from step 2, we have,

BD = 13 cm, that is, 

BA + AD = 13 cm

⇒ BA + AC = 13cm, because we have AD = AC (from above)

This is the justification for the construction that has been done in the question.

Hope it helps you!