Page 167 - Mathematics_Form_3

Circles

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4. Suppose AB is a chord of a then TC bisects the angle between

circle, O is the centre, and C is a the tangents, as well as the angle
point on the circumference, then between the two radii.
∠AOB = 2 × ∠ACB.
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13. Suppose AB is a chord of a circle
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5. Suppose AB is a diameter of and AT is a tangent. If C is in the
a circle and C is a point on the alternate segment, then
circumference, then ∠ACB = 90 ° . ∠TAB = ∠ACB.
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6. Suppose AB is a chord of a
circle, and C and D are points Revision exercise 5
on the circumference in the same
segment, then ∠ACB = ∠ADB. 1. Find the angles subtended at the

7. A cyclic quadrilateral has all its circumference and centre of a circle
vertices on a circle. of radius 4.8 cm by a chord 3.0 cm
long.
8. Suppose ABCD is a cyclic
quadrilateral, then 2. A chord XY of a circle of radius
∠DAB + ∠DCB = 180 ° . 6.8 cm subtends an angle of 42° at
the centre of the circle. Find the
9. If AB is a chord of a circle, then difference in length between the

the perpendicular bisector of AB chord XY and the minor arc XY

passes through the centre of the (Use π = 3.14).
circle. ¯ 3. Find in terms of π the lengths of
Mathematics for Secondary Schools 11. A tangent to a circle touches the (a) b 30º C a
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the arcs marked a, b, and c in each
10. If AB and CD are parallel chords,
of the following figures if the radii
then the two arcs between them
of the two circles is 6 cm.
are congruent.

circle at one point. A tangent is
perpendicular to the radius at the

point of contact. The tangents
from a point to a circle are equal
in length. A O B

12. If two tangents are drawn from c
point T to a circle with centre at C,

160 Student\s Book Form Three

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MATHEMATIC F3 SB.indd 160