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Targeting Grade C
Angles
SSM1
GCSE Mathematics
Practice 1:: To recognise vertically opposite, alternate (Z), corresponding (F) and interior angles
Practice 2: To remember that angles in a triangle add up to 180º
Question 1
Practice 3: To remember that the angles in a quadrilateral add up to 360º
Practice 4:To work out sum of the interior angles of your polygon. A formula will help
Questions 2
Can you:
Use angle facts to calculate angles:
•Associated with parallel lines
•In a triangle
•Try some questions
•In a quadrilateral
•In any polygon
•Try some questions
If not you need
Angles associated with parallel lines
Click to begin
These are all parallel lines.
Click to continue
What is the connection between the yellow angles?
Click to continue
They are equal because the are in corresponding positions. They are
called corresponding angles
Click to continue
Notice that even though the size of the angles change, they are still equal.
Click to continue
They are equal because the are in corresponding positions. They are
called corresponding angles
Click to continue
These are vertically opposite angles.
Click to continue
What do you think the relationship is between them?
These angles are called
alternate angles.
They are equal.
Click to continue
What are the yellow angles called?
Click to continue
What are the blue angles called?
Click to continue
What is the link between the size of the yellow angles and the blue
angles?
Click to continue
These angles are called interior
angles.They are inside the parallel lines.
Click to continue
These are
also interior angles.
Click to continue
What do you think is the relationship between these?
Click to continue
136ºx
Find the missing angle marked x
95ºx
Find the missing angle marked x
125º
x
Find the missing angle marked x
105º x
zy
Find the sizes of the angles marked with letters
95º
a
c
b
Click for answers
X = 75º
Y = 105º
Z = 105º
a = 85º
b = 85º
c = 85º
Which angle do you need to work out first?
124º
x
y
Find the missing angles marked x and y
118º
x
Find the missing angle marked x
Go back to objectives
Angles in a triangle
What are the yellow angles called?
What are the red angles called?
Click to continue
Notice the red, yellow and green angles.
Click to continue
They are inside the purple triangle.
and on a straight line.
So the number of degrees in a Triangle
must be the same as in a straight line.
Click to continue
Which is?
a
60º 45º
Find angle a
b
37º
48º
Find angle b
c
40º
c
Find the angles marked c
3x
x
2xBack to objectives
What is the size of each of the angles?
Questions 1
Questions to practice angles associated with
parallel lines and in triangles
SSM 1Conundrum - Calculating angles 1
You can use what you know about angles to calculate angle and angle .There is more than one way to calculate these angles.
How many different ways are there?Explain.
Are there any other angles here that you could calculate?Explain
Calculating angles 2
Explain how you would calculate angle and angle The line AD looks as though it could be equal to the line CD. Is it?How do you know?
Back to objectives
Angles in a quadrilateral
Every quadrilateral can be divided into two triangles each containing 180º
2 x 180 = 360º
1
2
1
2
12
1
2
70º x
y
Find the missing angles
75ºx
y
Find the missing angles
x
60º
55º
x = º
145º
x
100º
55º x = º
95º
x
200º
25º
x = º
115º
x x
x = º
2x
2x
Back to objectives
Angles in a polygon
Formula to use to calculate the sum of the
interior angles in a polygon
(n – 2) x 180 = total number of degrees
n is the number of sides in the polygon
If you forget this formula you can always divide the shape into triangles
Can be divided into three triangles
Each triangle has an angle sum of 180º
So, angle sum of the pentagon is 3 x 180 = 540º
1
2
3
How many sides does the shape have?
Apply the formula (n-2) x 180 to find the sum of the interior angles
If this is a regular hexagon , calculate the size of each of the interior angles
Click for answers
6
(6 – 2) x 180
= 4 x 180
= 720º
720 ÷ 6 = 120º
x
70º 70º
x = º
140º
130º
x
110º 100º
x = º
110º
120º
x
140º
140º
x = º
140º
140º
80º
Back to objectives
Questions 2
Practice questions using angles associated
with quadrilaterals and polygons
Back to objectives