1. The document discusses the exterior angle property of triangles, which states that the exterior angle of a triangle is equal to the sum of its two opposite interior angles. 2. To demonstrate this, students are instructed to cut out triangles from different colored paper, name the angles, and place the interior angles adjacent to each other to show they cover the exterior angle. 3. By observing this activity, students can infer that the measure of the exterior angle is equal to the sum of the measures of its two opposite interior angles.

2. What I Expect As A Teacher

3. General Instructions

4. Quote of the day

5. Topic
Exterior angle property

6. Learning Outcomes
Learners will be able to
1. Assimilate the concept of medians and altitudes
of a triangle
2 . acquire knowledge about median and altitude
of a triangle
3 . examine the relation between the interior
opposite angles and the exterior angle of a triangle

7. Dear students let us do an activity
1.Take two cut outs of same triangles with
different colours papers.
2.Paste one of the cut in paper , and name it as
ΔABC. Produce its base BC to D.
3.Name the angles which are interior of the
triangle ABC ? ∠A, ∠B, ∠C
4.Name the angle which is exterior of ΔABC ?
∠ACD
5.Now cut out ∠A, ∠B and place them adjacent to
each other.
6.Do these two pieces entirely cover ∠ACD? Yes

8. What did you observe infer from
above activity?
m∠ACD = m∠A +m ∠B
That is exterior angle of a triangle is
equal to sum of its two opposite
interior angle.
Parameters

9. [A]Cutting
of triangles
[1m]
[B]Identif
ying
interior
angles
[1m]
[C]Identif
ying
exterior
angles
[1m]
[D]Ident
ifying
opposite
interior
angles
[1m]
[F]Result Total
[5m]

10. Evaluation
Class Test:
Answer the following questions
1. Find the value of the unknown exterior angle x in the following
diagrams:
2. Find the value of the unknown interior angle x in the following figures:
3.What can you say about each of the interior opposite angles,
when the exterior angle is
(i) a right angle? (ii) an obtuse angle? (iii) an acute angle?
4. Can the exterior angle of a triangle be a straight angle