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Section 7.6: Circles and Arcs Section 7.7: Areas of Circles, Sectors, and Segments Section 7.8: Geometric Probability. Review of Circles. You name a circle by its center point: circle P. Formulas: Area A = r 2 Circumference C = 2 r = d
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Section 7.6: Circles and Arcs Section 7.7: Areas of Circles, Sectors, and Segments Section 7.8: Geometric Probability
Review of Circles You name a circle by its center point: circle P Formulas: AreaA = r2 CircumferenceC = 2r = d = 3.141592654 . . . (on a scientific calculator) Most people use = 3.14 P
CD CX Arcs (parts of circles) An arc is made up of two points on a circle and all the points of the circle needed to connect those two points by a single path. X CD Semi-circle: half Minor arc < semicircle Major arc > semi circle symbol DCX
E F A central angle is an angle whose vertex is the center of the circle. 120 L
EF=120 Measure of Arc AB (degrees) = measure of the central angle Length of Arc AB (partial circumference) E F 6 cm 120 L
B A P C D Identify at least one minor arcs, at least one major arcs, and both semi-circles in Circle P.
Q 320 O 12 cm R S Find the measure of arc RS, the length of arc SR (in terms of ), and the length of arc SQR (in terms of π).
Sectors A (0, 8) A sector of a circle is a region bounded by two radii and an arc of a circle. The pink area shows sector AXB. A sector has an area. B (8, 0) X (0, 0)
C 6 cm 100 A B Find the area of shaded sector ACB in terms of .
Chords A chord is a line segment joining two points on a circle. (A diameter is a special chord that passes through the circle center.) RQ and RS are chords. An inscribed angle is an angle whose vertex is on a circle and whose sides are determined by two chords of the circle. QRS is an inscribed angle. The measure of an inscribed angle is half the measure of its intercepted arc. Q S R
Segments E A segment of a circle is a region bounded by an arc and the chord having the same endpoints as the arc. The yellow area shows a segment. F 120 24 ft L
Find the area of shaded segment, in terms of , then rounded to the nearest tenth. E F 120 4 ft L
Circle S has a diameter of 10 in and an inscribed square. Find the area of the shaded regions in terms of . 10 in S
Find the area of the shaded region. Round to the nearest whole number. 13 cm 60
Find the area of the shaded region. Round to the nearest whole number. 22 in 90
Find the area of the shaded region. Express your answer in terms of . 7 m
Geometric Probability Instead of the ratio of favorable outcomes to total possibilities, compare the target area to the entire area. d = 12 in A dart lands on a random point on the circular target shown. What is the probability that it lands on the 3-in square bull’s-eye?
A park contains two circular playgrounds. One has a diameter of 60 m and the other has a diameter of 40 m. How much greater is the area of the larger playground? (Round to the nearest whole number.) A circle has an 8-in radius. Find the area of a sector whose arc measure is 135. Express your answer in terms of .
Homework 7.6-7.7 Walsh Worksheet