We use the formula to find the sum of the interior angles of an octagon, then we can divide it by the number of sides it has.
[tex]\sf180(n-2)[/tex]
Where 'n' is the number of sides.
An octagon has 8 sides, so we have:
[tex]\sf180(8-2)[/tex]
Subtract:
[tex]\sf180(6)[/tex]
Multiply:
[tex]\sf1080[/tex]
This is the sum of all the angles in a regular octagon, and since an octagon has 8 angles, we divide by 8 to find the measure of one angle.
[tex]\sf1080\div8=\boxed{\sf135}[/tex]
