The Proof of the Cyclic Quadrilateral Theorem

A cyclic quadrilateral is a quadrilateral inscribed in a circle. A polygon that is inscribed in a circle is a polygon whose vertices are on the circle. Some of the inscribed polygons are shown in the next figure. In this post, we are going to show a special property of one inscribed polygon which is […]
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The Angle Secant Theorem

A secant is a line that intersects a circle at two points. In the figure below, is formed by two secants. The angle intercepts two arcs and . In this post, we will prove that the measure of the angle formed by two secants intersecting outside a circle is half the difference of the arcs […]
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