Circle Theorems

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Circle Theorems
The angle at the centre is twice the angle at the
circumference for angles which stand on the same
arc.
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Circle Theorems
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Circle Theorems
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Circle Theorems
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Circle Theorems
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Circle Theorems
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Circle Theorems
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Circle Theorems
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Circle Theorems
1) The two tangents from a point to a circle are
equal in length. 2) Angles subtended at the
circumference by equal arcs are equal. 3) If a
pair of opposite angles of a quadrilateral add up
to 180o then it is a cyclic quadrilateral. 4)
The angle in a semicircle is a right angle. 5)
The exterior angle of a cyclic quadrilateral is
equal to the interior opposite angle. 6) The
straight line from the centre of a circle at
right angles to a chord bisects the chord.
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Circle Theorems
7) A tangent is perpendicular to the radius at
the point of contact. 8) The circle drawn on the
hypotenuse of a right-angled triangle as
diameter passes through the opposite vertex. 9)
Angles in the same segment are equal. 10) The
straight line from the centre of a circle to the
mid-point of a chord is perpendicular to the
chord. 11) The opposite angles of a cyclic
quadrilateral add up to 180o. 12) The angle at
the centre is twice the angle at any point on
the circumference subtended by the same arc. 13)
Equal chords are equidistant from the centre of a
circle.