Steps of construction of △ABC:
Step 1:
Draw the base line BC of the length 5.8 cm.
Step 2:
Measure the angle C with your protractor. Make a mark at 30 degrees and draw a line from C passing through the mark.
Step 3:
Measure the angle B with your protractor. Make a mark at 30 degrees and draw a line from B passing through the mark.
Step 4:
Name the point of intersection of these two lines as A and the △ABC is complete, as shown below.
Now, from the above construction we see that the sum of length of the side AC and AB is 6.8 cm