Circles Lesson 1 April 27 09
Transcript of Circles Lesson 1 April 27 09
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Circle Geometry
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diameter
chord
secant
a chord that passes throughthe centre of the circle
a line that contains a chord
a line segment
that joins
two points on
the circle
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Perpendicular bisector theorem:The perpendicular bisector of a chord contains the centre of the circle. The perpendicular bisectors of two nonparallel chords intersect at the centre of the circle. The perpendicular from the centre of a circle to a chord bisects the cord.
The line segment joining the centre of a circle and the midpoint of a chord is perpendicular to the chord.
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A
B
C
O5 3
Find the length of AO, and AB
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A
B
C
D
E
O
10
8
Find the length of OE
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A chord that is 10 cm long is 12 cm from the centre of a circle. Find the length of the radius.
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A road tunnel under a river is built inside a cylinder of radius 5.35 m. The road surface, AB, is 1.85 m above the lowest point of the cylinder. What is the width of the road to the nearest hundreth of a metre?
A B
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Questions 1 6
Exercise 30