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Engage in geometry investigation on inscribed angles, intercepted arcs, and the relationships within circles. Analyze angles RTS, RUS, RVS, compare angles, and apply theorems and practices in circle geometry.
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Geometry Inscribed Angles and Other Relationships
Vocabulary • Central Angle – an angle whose vertex is on the center of a circle. The arc measure is equal to the measure of the central angle. • Inscribed Angle – an angle whose vertex is on a circle. • Intercepted Arc – the arc that lies between an inscribed angle.
Investigation Activity • Use trace paper to create angles RTS, RUS, and RVS. • Compare the four angles to each other (RPS, RTS, RUS, RVS). What do you notice?
Draw a right triangle in your circle.How do you know it is a right triangle? • Draw a quadrilateral in your circle. What can you conclude about the angles of your quadrilateral?
Practice m∠BAC = = = 2 = m∠BAC = m∠BAC = m∠BAC =
Practice 3y + 3x = 180° y + x = 60° y = 60° - x 2y + 5x = 180° 2(60°-x) +5x = 180° 120° -2x +5x = 180° 3x = 60° x = 20° 2x + 100° = 180° -100° -100° 2x = 80° x = 40 y + 87° = 180° -87° -87° y = 93° y =60° - 20° y =40°
Practice • Since the intersection occurs inside of the circle. We add the two intercepted arcs formed by the angle and its vertical angle.
Practice • Since the intersection occurs outside of the circle. We subtract the arcs formed by the angle and then divide by two.
Practice • Since the intersection occurs outside of the circle. We subtract the arcs formed by the angle and then divide by two.
Exit Ticket Homework • Copy down one of the pictures and examples that we completed in class and turn it in. • Pg. 617: 9-23 odd • Pg. 624: 9-27 odd