2. Name of the teacher: MEENU M
Name of the school: Standard & Division: X
Subject: Mathematics Strength:
Unit: Tangent Duration: 45’
Topic: Lines & Circle Date:
Curricular Statement
Getting an actual magnitude about the tangents on a circle
Content Analysis
Terms: Tangents, circle, triangle, square, angle.
Facts: - A line just touches the circle
- Such line is called tangents
Concept: Tangents on a circle
Learning Outcomes
Remembering : The students will be able to recall about circles, its peculiarities, chord, tangent...
: The students will be able to recognize about circles, its peculiarities, chord, tangent…
Understanding : The students will be able to understand about tangent, circle, its peculiarities…
: The students will be able to explain the idea of tangent, circle, its peculiarities…
Applying : The students will be able to apply the concept tangent in unfamiliar situation.
3. : The students will be able to use the information in another familiar situation.
Analyzing : The students will be able to analyze the concept into parts to explore understanding
and relationships.
: The students will be able to deconstruct new idea about tangent on a circle.
Evaluating : The students will be able to justify a decision about the concept tangent on a circle.
: The students will be able to judge the adequacy and inadequacy of the data.
Creating : The students will be able to generate new idea about the concept tangent on a circle.
Skill : The students will be able to draw figures with speed and accuracy.
Interest : The students will be able to develop interest to do mathematical calculations.
Pre-requisites
The students know
to draw circles
to draw triangles
to measure angles…
Teaching-learning resources
Laptop- to show the pictures of tangents
Geometrical instruments to draw figures
Ordinary classroom equipments
Classroom interaction procedure Pupils response
Preparation
To test the previous knowledge of students teacher ask some
questions.
Teacher show a picture of circle of some radius, then said to draw a
square around it as shown below.
4. How did you draw the sides?
Next draw a circle and this time, draw an equilateral triangle around it
as shown below.
In the picture of square and triangle, each side passes through how
many points of the circle?
Have you seen before, instances where a line passes through a single
point on a circle?
Let’s look at such relationships between lines and circle…
Presentation
We can do it with an example,
For that we want to draw ΔABC with AB= 6 cm, AC= 3 cm and an angle B
of 20˙.
To draw such a figure at first draw a circle of radius 3cm and mark the
centre as A
Students also draw figure with the help of instruction given by teacher.
For square circle touches 4 sides
and in triangle also circle touches 3
sides
Yes
5. Now draw AB of length 6cm
Since the angle B is 20˙, lets draw a line slant through B:
How many times line touches the circle?
It is clear that the line touches the two point in the circle at C1 and at C2
Two times
6. Thus we get two triangles
ΔABC1
A
and ΔABC2
Now we can draw an another angle of 30˙
7. How many times line touches the circle?
How many triangles did we get?
What is the name of that triangle?
The triangle is
Now we can look what happen when we draw an angle of 40˙.
Only one time
One
ΔABC
The line has nothing to do with the
circle.
8. What happen to the circle and to the line?
Generalization
Can you say what about the 30˙ line?
Such a line is called a tangent to the circle.
“SO TANGENT IS A LINE THAT JUST TOUCHES A POINT ON THE CIRCLE”
Application
Class assignment
Find how many tangents are there in the given figure?
Review
How can we define a tangent on a circle?
It just touches the circle.
There are two tangents in this
figure.
9. Home Assignment
How many tangents can be drawn in a circle, try to draw it.
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