Toán Tiếng anh: Hai góc đối đỉnh

Week 1 
Period 1 § 1. TWO VERTICAL OPPOSITE ANGLES 
I/ Objectives: 
- The knowledge: Student will know the concept vertical opposite angles and properties of 
vertical opposite angles 
- The skills: Students have ability to identify quickly vertical opposite angles in life and 
figure. Students have skills presenting Math solutions in English well 
- The attitude: Students have self-discipline in learning and group activities. There is a 
dynamic, creative life. And the practice careful in draw figure 
II/ Vocabulary: 
- Vertical: Thẳng đứng 
- Opposite: Đối ngược nhau 
- Two vertical opposite angles: Hai góc đối đỉnh 
- Perpendiculars line: Đường thẳng vuông góc 
- Parallel line: Đường thẳng song song 
III/ Teaching and students aids: Book, notebook, ruler 
IV/ Content: 
 1/ Class organization: 
- Greeting 
- Checking attendance: How many students absent on today ? 
2/ Introduced 
- Perpendiculars line 
- Parallel line 
- Vertical opposite angles 
3/ New lesson: 
Teachers activities Students activities Content 
We call 

1O , 

3O a pair of 
vertically opposite angles. Let us 
see some real life exmples for 
vertically opposite angles: 
Who can observe the side and 
the vertices of 1O , 

3O ? 
Look and write down 
A student represents 
answer question 
Speak define two vertical 
1/ What vertical opposite 
angles are ? 
- In Figure 1. Two lines xy and 
x’y’ cut at O 
Fig.1 
? 1 The 1O and 

3O have each 
other side of angle is opposite 
ray of side of angle other 
Define: Two vertical opposite 
angles are two angles each other 
Do 

2O and 

4O have two vertical 
opposite angles ? Why ? 
Give remark to student answers 
Solve simlar exercises 
1/82 
Fig.2 
2/82 
Give remark to student answers 
In figure 1. 
a/ Measure 1O and 

3O . 
Compare us 
b/ Measure 

2O and 

4O . 
Compare us 
c/ Guess result to a and b 
Give remark to student answers 
opposite angles 
A student represents 
answer question 
Two students represent 
write on the board 
a/ 
xOy vaø ' 'x Oy are two 
vertical opposite angles 
b/ 
'x Oy vaø 'xOy are two 
vertical opposite angles 
a/ Two angles each other 
side of angle is opposite 
ray of side of angle other 
are two vertical opposite 
angles 
b/ When two line which 
intersect make two pairs of 
vertically opposite angles 
equal 
A student represents 
answer question 
Look and write down 
side of angle is opposite ray of 
side of angle other 
? 2 
2O and 

4O are two vertical 
opposite angle. Because they 
have each other side of angle is 
opposite ray of side of angle 
other 
2. Properties of two vertical 
opposite angles: 
? 3 
a/ 

1O = 

3O 
b/ 

2O = 

4O 
c/ When two line which 
intersect make two pairs of 
vertically opposite angles equal 
Prove: 
Let xy and x’y’ be two lines 
which intersect at O making 
angles 1O , 

2O , 

3O and 

4O 
We want to prove that 

1O = 

3O ; 

2O = 

4O . Now 

1O =180
o
 - 

2O ( because 

1O ,

2O 
form a linear pairs so 

1O +

2O =180
o
 ) (1) 
Similarly 

3O = 180
o
- 

2O ( 
Read properties 
because 

3O ,

2O form a linear 
pairs so 

3O +

2O =180
o
 ) (2) 
Therefore 

1O =

3O ( by ) (1) 
and (2) ) 
Properties: ( When two lines 
intersect ) The vertically 
opposite angles so form are 
equal. 
4/ Consolidation: 
Exercise: Who can do it ? 
In Fig.3 identify pairs of vertically opposite angles 
3/82. Draw zz’ cutting tt’ at A, write name pairs of vertically opposite angles 
4/82. Draw  60oxBy . Draw vertically opposite angles with xBy . How much the xBy 
degree ? 
5/ Homework: 
- Review all the lesson and exercise that we do today 
- Exercise 3, 4 SGK/82; 3, 4, 5, 7 SBT/74 and aids practise