Find out the value of one angle of a triangle on the basis of the value of two given angles. S. No. Measure of the 1 st angle Measure of the 2 nd angle Value of the 3 rd angle = 180 ° - 1 st angle + 2 nd angle 1 40 ° 60 ° 180 ° - 40 ° + 60 ° = 80 ° 2 40 ° 35 ° 3 45 ° 95 ° 4 70 ° 50 °

We are asked to find the value of one angle of a triangle on the basis of the value of two given angles. We know that by the angle sum property, the sum of all angles of a triangle is 180 ° . That is, in △ A B C , ∠ A + ∠ B + ∠ C = 180 ° . The given measures of two angles of the second triangle are 40 ° & 35 ° . Let the third angle be x ° . Then, 40 ° + 35 ° + x ° = 180 ° ⇒ x ° = 180 ° - 40 ° + 35 ° ⇒ x ° = 180 ° - 75 ° ⇒ x ° = 105 ° Now, the measures of two angles of the third triangle are 45 ° & 95 ° . So, the third angle = 180 ° - 45 ° + 95 ° = 180 ° - 140 ° = 40 ° Similarly, the measures of two angles of the fourth triangle are 70 ° & 50 ° . So, the third angle = 180 ° - 70 ° + 50 ° = 180 ° - 120 ° = 60 ° Hence, the completed table is as follows. Find out the value of one angle of a triangle on the basis of the value of two given angles. S. No. Measure of the 1 st angle Measure of the 2 nd angle Value of the 3 rd angle = 180 ° - 1 st angle + 2 nd angle 1 40 ° 60 ° 180 ° - 40 ° + 60 ° = 80 ° 2 40 ° 35 ° 180 ° - 40 ° + 35 ° = 105 ° 3 45 ° 95 ° 180 ° - 45 ° + 95 ° = 40 ° 4 70 ° 50 ° 180 ° - 70 ° + 50 ° = 60 °

Fill in the table with the names of adjoining interior angles, distant angles and the exterior angles of the triangle given below. Triangle Name of the triangle Name of the exterior angle Adjoining interior angle Distant interior angle I II

Given triangle is We are asked to find the names of the adjoining interior angles, distant interior angles and the exterior angles of the triangle. If one of the arms of a triangle is extended out of the closed area, it makes an angle, which is called the exterior angle. Each exterior angle is attached to an interior angle, which is complementary angle to the exterior angle. This interior angle which is joined to the exterior angle is known as the adjacent interior angle and the other two interior angles are known as distant interior angles. Since the three vertices of the triangle are P , Q & R , the name of the triangle is △ P Q R . It can also be called as △ Q R P , △ P R Q , △ Q P R and so on considering the order of vertices. The side R Q is extended to M to make the exterior angle. So, the exterior angle thus formed is ∠ P Q M . The adjoining interior angle, which makes supplementary angle with the exterior angle is ∠ P Q R . So, the other two distant interior angles are ∠ Q P R & ∠ Q R P . Hence, the completed table is as follows. Triangle Name of the triangle Name of the exterior angle Adjoining interior angle Distant interior angle I II △ P Q R ∠ P Q M ∠ P Q R ∠ Q P R ∠ Q R P

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For the triangle given below, write the names of the vertices, arms and the angles.

Important Questions on Triangle and Quadrilateral

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6th Chhattisgarh Board

IMPORTANT

MATHEMATICS CLASS - 6>Chapter 9 - Triangle and Quadrilateral>ACTIVITY 2

For the triangle given below, write the names of the vertices, arms and the angles.

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6th Chhattisgarh Board

IMPORTANT

MATHEMATICS CLASS - 6>Chapter 9 - Triangle and Quadrilateral>ACTIVITY 2

For the triangle given below, write the names of the vertices, arms and the angles.

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6th Chhattisgarh Board

IMPORTANT

MATHEMATICS CLASS - 6>Chapter 9 - Triangle and Quadrilateral>ACTIVITY 3

Measure the internal angles of the triangle given below with the help of your protractor and write them in the given table. Find the sum of the angles that you have measured for the triangle.

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Triangle	$∠ A$	$∠ B$	$∠ C$	$∠ A + ∠ B + ∠ C$ The sum of all angles

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6th Chhattisgarh Board

IMPORTANT

MATHEMATICS CLASS - 6>Chapter 9 - Triangle and Quadrilateral>ACTIVITY 3

Measure the internal angles of the triangle given below with the help of your protractor and write them in the given table. Find the sum of the angles that you have measured for the triangle.

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Triangle	$∠ A$	$∠ B$	$∠ C$	$∠ A + ∠ B + ∠ C$ The sum of all angles

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6th Chhattisgarh Board

IMPORTANT

MATHEMATICS CLASS - 6>Chapter 9 - Triangle and Quadrilateral>ACTIVITY 3

Measure the internal angles of the triangle given below with the help of your protractor and write them in the given table. Find the sum of the angles that you have measured for the triangle.

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Triangle	$∠ A$	$∠ B$	$∠ C$	$∠ A + ∠ B + ∠ C$ The sum of all angles

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6th Chhattisgarh Board

IMPORTANT

MATHEMATICS CLASS - 6>Chapter 9 - Triangle and Quadrilateral>ACTIVITY 3

Measure the internal angles of the triangle given below with the help of your protractor and write them in the given table. Find the sum of the angles that you have measured for the triangle.

Question Image

Triangle	$∠ A$	$∠ B$	$∠ C$	$∠ A + ∠ B + ∠ C$ The sum of the angles

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6th Chhattisgarh Board

IMPORTANT

MATHEMATICS CLASS - 6>Chapter 9 - Triangle and Quadrilateral>ACTIVITY 3

Find out the value of one angle of a triangle on the basis of the value of two given angles.

S. No.	Measure of the $1^{st}$ angle	Measure of the $2^{nd}$ angle	Value of the $3^{rd}$ angle $= 180 ° - (1^{st} angle + 2^{nd} angle)$
$1$	$40 °$	$60 °$	$180 ° - (40 ° + 60 °) = 80 °$
$2$	$40 °$	$35 °$
$3$	$45 °$	$95 °$
$4$	$70 °$	$50 °$

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6th Chhattisgarh Board

IMPORTANT

MATHEMATICS CLASS - 6>Chapter 9 - Triangle and Quadrilateral>ACTIVITY 4

Fill in the table with the names of adjoining interior angles, distant angles and the exterior angles of the triangle given below.

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Triangle	Name of the triangle	Name of the exterior angle	Adjoining interior angle	Distant interior angle
				I	II

For the triangle given below, write the names of the vertices, arms and the angles.

Important Questions on Triangle and Quadrilateral

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