## Thinking Mathematically (6th Edition)

$1080^o$
RECALL: The total measurement of the angles of a polygon with $n$ sides is given by the formula: $180^o(n-2)$ An octagon has 8 sides. Thus, the sum of the angles inside an octagon is: $=180^o(8-2) \\=180^o(6) \\=1080^o$