MATHS TIPS : CIRCLES
Form 2 :
Circles diameter = radius + radius
d = 2r
Formula for circles as follow :
1) d = 2r
2) r = d/2
3) Circumference = 22/7 X d
= 2 X 22/7 X r
4) Arc length = x°/360° X 2 X 22/7 X r
5) Area = 22/7 X r²
6) Area of sector = x°/360° X 22/7 X r²
Form 3 :
To learn circles you need to know the following:
1. A diameter is a straight line that passes through the centre of a circle.
2. A radius that is perpendicular to a chord divides the chord into two equal parts.
3. The features of triangles in Pythagoras Theorem.
4. An angle subtended at the centre by an arc is twice the size of the angle subtended by the same arc at the circumference.
5. The angle subtended at the circumference in a semicircle is 90°.
6. The straight line that joins any two points on the circumference and does not pass through the centre of a circle is called a chord.
7. The relationship between interior opposite angles of cyclic quadrilaterals = 180°.
8. The exterior angles and the corresponding interior opposite angles of cyclic quadrilaterals.
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