Draw the base line AB of the length 6 cm.
Measure the angle A with your protractor. Make a mark at 90 degrees and draw a line from A passing through the mark.
Draw an arc with centre at B and radius 10 cm. The point at which this arc cuts the line through A is the required point C.
Thus △ABC is formed.
From the above construction, we see that the length of side AC is 8 cm.