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PSSA Coach Lesson 14. Circles M11.C.1.1.1 M11.C.1.1.2. Unit 3: Geometry. Key Concepts. Definitions relating to a circle: Circle: all points in a plane that are equidistant from one point, the center . Radius: a segment form the center to one point on a circle.
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PSSA Coach Lesson 14 Circles M11.C.1.1.1 M11.C.1.1.2 Unit 3: Geometry
Key Concepts • Definitions relating to a circle: • Circle: all points in a plane that are equidistant from one point, the center. • Radius: a segment form the center to one point on a circle. • A chord is a segment with both endpoints on the circle. • Diameter: a chord that passes through the center of the circle. • A central angle is an angle whose vertex is the center of the circle.
Key Concepts • The central angle forms a minor arc and a major arc. Arcs, like circles, are measured in degrees. • The degree measure of a major arc is equal to 360˚ - the degree measure of its minor arc. • The degree of a minor arc is equal to the measure of its central angle. • The length of arc l = (D/360) * 2πr; where r is the radius and D is the measure in degree of the arc.
Key Concepts • Semi-circle is a half circle. • A tangent is a line in the same plane as a circle that touches the circle at one point. • An inscribed angle is an angle whose vertex is on the circle and whose sides are chords of the circle. • The outer angle is two times as great the inscribed angle.
Key Concepts • Square ABCD is inscribed in circle O. Assume that the radius of the circle is 4cm. • Find • mLAOB • mAB • length of BC • length of BAC
Key Concepts • Example 2: • PM is a tangent line to circle O and point M. • Find LOMP. • Find OP.
Independent Practice • Do “Check it out with the Coach” on Pg 163. • Take about 3 minutes on your own, then we will discuss it.
Now Do… • Do Lesson 14 Practice on Pgs. 164-165#1-9all • SHOW ALL WORK!!!! NO WORK = NO CREDIT • For the open-ended: Write your response and justify the for answer with a sentence!!!