We can see that ∠ACB and ∠ACD are supplementary angles. This means they have a sum of 180 degrees. If ∠ACD is 108 degrees, then ∠ACB can be found through this equation: [tex]180 - ACD = ACB[/tex]
--> [tex]180 - 108 = ACD[/tex]
This means that ∠ACB is 72°.
