Recall that the measure of each interior angle of a regular n -gon is ( n-2)180^(∘) n. To find the measure of an interior angle of a dodecagon we have to substitute 12 for n in this expression.
( 12-2)180^(∘)/12= 150^(∘)
Because there are 12 sides, there are 12 angles. We can multiply this angle measurement by 12 to find the sum of the angles.
150^(∘) * 12 =1800^(∘)
