A regular octagon is inscribed in a circle of radius 15.8 cm. Find the perimeter of the octagon.
What I would do is draw a diagram of your problem. Draw a circle, then draw a line straight up and down through the centre of the circle, then another line across the circle through the centre again, bacsically cutting the circle into ...
The method for finding the Perimeter of an Octagon within a Circle is described.