http://www.ck12.org Chapter 9. Circles
Example C
Findm^6 DABin
⊙
C.
BecauseCis the center,DBis a diameter. Therefore,^6 DABinscribes semicircle, or 180◦.m^6 DAB=^12 · 180 ◦= 90 ◦.
Watch this video for help with the Examples above.
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/52423CK-12 Foundation: Chapter9InscribedAnglesinCirclesB
Concept Problem Revisited
You can take the picture from anywhere on the semicircular walking path. The best place to take the picture is
subjective, but most would think the pale green frame, straight-on, would be the best view.
Vocabulary
Acircleis the set of all points that are the same distance away from a specific point, called thecenter. Aradiusis
the distance from the center to the circle. Achordis a line segment whose endpoints are on a circle. Adiameter
is a chord that passes through the center of the circle. The length of a diameter is two times the length of a radius.
Acentral angleis an angle formed by two radii and whose vertex is at the center of the circle. Aninscribed angle