\r\n In geometry, an inscribed angle is defined as the angle subtended at a point on the circle by two given points on the circumference of the circle.\r\n For example, in the figure shown below, angle marked by 'a' is the inscribed angle subtended by points B and C on point A.\r\n
\r\n\r\n A central angle is defined as the angle subtended at the center of the circle by two given points on the circumference of the circle.\r\n For example, in the figure shown below, angle marked by 'b' is the central angle subtended by points B and C on the center of the circle.\r\n
\r\n\r\n Inscribed angle theorem states that the measure of an inscribed angle (shown by 'a' in the figure below) subtended by any two points on the circle is\r\n half of the measure of the central angle (shown by 'b' in the figure below) subtended by those two points.\r\n
\r\n\n The purpose of the interactive illustration below is to help students understand the inscribed angle theorem.\r\n Points A, B and C are three movable points located on the circumference of the circle with center at O.\r\n The angle 'a' is the inscribed angle by arc BC at A while the angle 'b' is the central angle subtended by arc BC at the center of the circle. For any choice of A, B, and C, you will notice that the angle 'a' is always half the value of angle 'b'.\r\n
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