### Theory:

Construct the circumcentre of the $$ΔABC$$ with $$AB =5 cm$$, $$∠A = 60°$$ and $$∠B = 80°$$. Also draw the circumcircle and find the circumradius of the $$ΔABC$$.

Rough sketch:

Step 1: Draw $$ΔABC$$ with the given measurements.

Step 2: Build a perpendicular bisector along both side ($$AC$$ and $$BC$$) and let it meet at $$S$$, which is the circumcenter.

Step 3: $$S$$ as center and $$SA = SB = SC$$ as radius, draw the circumcircle to pass through $$A$$, $$B$$ and $$C$$. And the circumradius measured $$= 3.9 cm$$.