The experiment to determine Verify that in a Triangle, Longer Side has the Greater Angle are part of the Class 9 Maths Lab Manual provides practical activities and experiments to help students understand mathematical concepts effectively. It encourages interactive learning by linking theoretical knowledge to real-life applications, making mathematics enjoyable and meaningful.
Maths Lab Manual Class 9 CBSE Verify that in a Triangle, Longer Side has the Greater Angle Experiment
Determine Verify that in a Triangle, Longer Side has the Greater Angle Class 9 Practical
OBJECTIVE
To verify experimentally that in a triangle, the longer side has the greater angle opposite to it.
Materials Required
- Cardboard
- Coloured glazed papers
- White paper
- Tracing paper
- Scissors
- Geometry box
- Sketch pens
- Adhesive
Prerequisite Knowledge
Concept of triangle and its properties.
Theory
For concept of triangle and its properties refer to Activity 12.
Procedure
- Take a cardboard of suitable size and by using adhesive, paste a white paper on it.
- Cut out a ΔABC from a glazed paper and by using adhesive, paste it on cardboard, (see Fig. 15.1)
- Measure the lengths of all the three sides of ΔABC and identify that which of them is longest.
- All the three angles of a triangle are to be marked, (see Fig. 15.2)
- Using a tracing paper, make the cut out of the angle opposite to the longest side SC, i.e. ∠A. (see Fig. 15.3)
- Compare the cut out of the angle with remaining angles. (see Fig. 15.4)
Demonstration
We came to know that ∠A > ∠B and ∠A > ∠C , BC > AC,
So, we get since ∠A > ∠B
Also, BC > AB, since ∠A > ∠C
Thus, we observe that the angle belongs to longer side is greater than the angle opposite to other side.
Observation
Length of side AB = ……….. , Length of side BC = ………. , Length of side CA = ………… ,
Measure of the angle opposite to the longest side = …………. ,
Measure of the other two angles = …………… and ………. ,
The angle opposite to the …………. side ……….. is than either of the other two angles.
Result
We have verified experimentally that in a triangle, the longest side has the greater angle opposite to it.
Application
The result can be useful in different geometrical problems.
Viva Voce
Question 1:
In the right angled triangle, which one is the longest side?
Answer:
Hypotenuse
Question 2:
Does sum of any two sides of a triangle is always smaller than the third side?
Answer:
No, because the sum of any two sides of a triangle is always greater than the third side.
Question 3:
Is it possible to draw a triangle having sides 7 cm, 3 cm and 10 cm?
Answer:
No, because the sum of any two sides of a triangle is always greater than the third side.
Question 4:
Which type of triangle, have any two sides equal?
Answer:
Isosceles triangle
Question 5:
Which type of triangle, have all sides equal?
Answer:
Equilateral triangle
Question 6:
Does the longer side has the smaller angle opposite to it in a triangle?
Answer:
No, the longer side has the greater angle opposite to it in a triangle.
Question 7:
If in ΔABC, ∠A > ∠B, then what can you say about the opposite sides of ∠A and ∠B?
Answer:
BC > AC, because ∠A is greater than ∠B, so side opposite to ∠A will also be greater than the side opposite to ∠B.
Question 8:
Which type of triangle, have all sides unequal?
Answer:
Scalene triangle
Suggested Activity
Verify experimentally the relation between unequal sides of a triangle and the angles opposite to them.
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