Since the circle touches the sides of the octagon at their midpoints, it is inscribed within the octagon. This means that the octagon's vertices lie on the circumference of the circle.
We know that the interior angles of an octagon sum up to 1080º. Therefore, the measure of each interior angle of the octagon is 1080º / 8 = 135º.
Since angle CDE is one of the interior angles of the octagon, it must also measure 135º.
ABCDEFGH is a regular octagon.
The circle, centre O, touches the sides of the octagon at their mid-points.
( a ) Show that angle CDE is 135º .
1 answer
1 answer