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This review covers essential concepts of central and inscribed angles in circles. It explains how the vertex position determines the angle's properties, illustrating that the arc of a circle is twice as large as its inscribed angle. Through multiple examples, we investigate different scenarios involving angle measures, including finding unknown variables. Additionally, we emphasize the properties of inscribed polygons, elaborating on supplementary angles and the significance of diameters in right triangles. This guide is perfect for reinforcing comprehension through practice problems.
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Case I:Central Angle: Vertex is ATthe center A P B
Case II:Inscribed Angle: Vertex is ON circle ANGLE ARC ARC ANGLE
160 The arc is twice as big as the angle!! 80
Find the value of x and y 120 x y
J K Q S M Examples 1. If mJK= 80 and JMK = 2x – 4, find x. x = 22 2. If mMKS= 56, find m MS. 112
Find the measure of DOG and DIG D 72˚ G If two inscribed angles intercept the same arc, then they are congruent. O I
If all the vertices of a polygon touch the edge of the circle, the polygon is INSCRIBED and the circle is CIRCUMSCRIBED.
a quadrilateral inscribed in a circle: opposite angles are supplementary. B A D C
If a right triangle is inscribed in a circle then the hypotenuse is the diameter of the circle. diameter
Q D 3 J T 4 U Example 3 In J, m3 = 5x and m 4 = 2x + 9. Find the value of x. x = 3
Example 4 In K, GH is a diameter and mGNH = 4x – 14. Find the value of x. 4x – 14 = 90 H K x = 26 N G Bonus: What type of triangle is this? Why?
Example 5 Find y and z. z 110 110 + y =180 y y = 70 85 z + 85 = 180 z = 95
Inscribed Quadrilaterals
If all the vertices of a polygon touch the edge of the circle, the polygon is INSCRIBED and the circle is CIRCUMSCRIBED.
Vocab • inscribed quadrilateral a quadrilateral whose vertices are on a circle • inscribed triangle a triangle whose vertices are tangent to a circle
If a right triangle is inscribed in a circle then the hypotenuse is the diameter of the circle. diameter
In K, GH is a diameter and m<GNH = 4x – 14. Find the value of x. 4x – 14 = 90 H K x = 26 N G
a quadrilateral inscribed in a circle: opposite angles are supplementary. B A D C
Find y and z z 110 + y =180 110 y = 70 y 85 z + 85 = 180 z = 95
Practice WS Get in your groups please. 12 problems
Homework WS Day 21 Inscribed Angles Choose even or odd problems