Answer:
720°
Step-by-step explanation:
The "n" in the formula refers to the number of sides. The polygon shown has 6 sides, so the sum of interior angles is ...
S = 180°(6 -2) = 720°
A(n)=4+4(n-1)
a(n)=4+4n-4
a(n)=4n
76=4n
n=19
The sum of any arithmetic sequence (series are infinite) is:
(a+a(n))(n/2)
The average of the first and last terms times the number of terms, in this case we found that n=19 so:
19(4+76)/2=760
