Part 3: Radius-tangent theorem
What to do:1 Use a compass to draw a circle with centre O, and mark
on it a point A.2 Draw at A, as accurately as possible, a tangent TA.3 Draw the radius OA.4 Measure the angle OAT with a protractor.5 Repeat the procedure above with another circle and
tangent.6 Copy and complete:
The tangent to a circle is ...... to the radius at the point
......Part 4: Tangents from an external point
What to do:1 Use your compass to draw a circle, centre O.2 From an external point P draw the two tangents to the
circle to meet it at A and B.3 Measure AP and BP.4 Repeat with another circle of different size.5 Copy and complete:
Tangents from an external point to a circle are ......You should have discovered the followingcircle theorems:Name of theorem Statement DiagramAngle in a
semi-circleThe angle in a semi-circle is
a right angle.ABCb =90oChords of a circle The perpendicular from the
centre of a circle to a chord
bisects the chord.AM=BM
GEOMETRY
PACKAGEGEOMETRY
PACKAGEABO
PT
AOACOBAMBOCircle geometry (Chapter 27) 549IGCSE01
cyan magenta yellow black(^05255075950525507595)
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(^05255075950525507595)
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Y:\HAESE\IGCSE01\IG01_27\549IGCSE01_27.CDR Monday, 27 October 2008 2:40:25 PM PETER