Angles facts

1. October 4, 2012
Angles
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1. Angle facts

2. October 4, 2012
The sum of the angles on a straight line is always 180º.
140º
40º
You can describe this rule using letters.
40+140=180
b
a
ab
Explanation
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3. October 4, 2012
40º
The sum of the angles round a point is always 360º.
140º
140º
40º
You can describe this rule using letters.
a + b + c + d 140+40+140+40=360
a
b
c
d
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Explanation

4. October 4, 2012
40º
When two lines cross, the opposite angles are equal.
140º
140º
40º
You can describe this rule using letters.
a
b
a = bc = d
c
d
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Explanation

5. October 4, 2012
The sum of the angles inside a triangle is always 180º.
You can describe this rule using letters.
a + b + c=180
a
b
c
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Explanation

6. October 4, 2012
Right-angle
Scalene
Equilateral
Isosceles
These are the four types of triangle.
Equal sides can be shown using a small ‘dash’.
Revise
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7. October 4, 2012
ba
The sum of the angles in a quadrilateral is always 360º.
63º
104º
124º
69º
=360
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++ +c d
a
b
c
d
6963104124
Explanation

8. October 4, 2012
The angles in this quadrilateral still add up to 360º, even
though it is a re-entrant shape.
You can see this if you think of it as two triangles.
180 + 180 = 360
Explanation
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9. October 4, 2012
Find the missing angles.
a
b
c
144º
88º
132º
78º
65º
144º
46º
85º
Practise
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