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# Very Short Answer Type Questions- Triangles Class 9 Notes | EduRev

## Class 9 Mathematics by Full Circle

Created by: Full Circle

## Class 9 : Very Short Answer Type Questions- Triangles Class 9 Notes | EduRev

The document Very Short Answer Type Questions- Triangles Class 9 Notes | EduRev is a part of the Class 9 Course Class 9 Mathematics by Full Circle.
All you need of Class 9 at this link: Class 9

Question 1. In a Î”ABC, BC = CA and âˆ  A = 50Â°, which is longer BC or AB?
Solution:
âˆµ âˆ  1 = âˆ  2  [âˆµ AC = BC]
and âˆ A = âˆ 1 = 50Â°

â‡’ âˆ  2 = 50Â°
âˆ´ âˆ  C = 180Âº - [50Â° + 50Â°] = 80Â°
Since, âˆ C > âˆ A
â‡’ AB > BC Thus, AB is greater.

Question 2. In Î”ABC, âˆ  B = 60Â° and âˆ  C = 63Â°. Name the greatest side.
Solution:
In Î”ABC, âˆ  B = 60Â° and âˆ  C = 63Â°

â‡’
âˆ  A = 180Âº - (60Â° + 63Â°) = 57Â°
â‡’ The greatest side is opp. to the greatest angle i.e., 63Â°
âˆ´ Side AB is the greatest.

Question 3. In Î”ABC, if BC = AB and âˆ  B = 80Â° then find the measure ofâˆ  A.
Solution:
BC = AB â‡’ âˆ A = âˆ C

âˆµ âˆ B = 80Â°
âˆ´ âˆ A + âˆ C = 180Â° - 80Â° = 100Â°
â‡’ âˆ A = âˆ C = 50Âº

Question 4. Which of the following is not the criterion for congruence of D s? (i) SAS, (ii) SSA, (iii) ASA, (iv) RHS
Solution:
SSA is not the criterion for congruency.

Question 5. If two angles are (30 âˆ  a)Âº and (125 + 2a)Âº and they are supplement of each other. Find the value of â€˜aâ€™.
Solution:
âˆµ (30 - a)Âº and (125 + 2a)Âº are supplement to each other.
âˆ´ (30 - a + 125 + 2a)Âº = 180Âº
â‡’ a = 180Âº - 125Âº - 30Âº = 25Âº
â‡’ Value of a = 25Â°

Question 6. Each of the equal angles of an isosceles triangle is 38Â°, what is the measure of the third angle?
Solution:
Let the third angle = x
âˆ´ x + 38Â° + 38Â° = 180Â°

â‡’ x = 180Â° - 38Â° - 38Â°
= 104Âº

Question 7. In an isosceles Î”ABC, AB = AC and âˆ  A= 80Â°. What is the measure of âˆ  B?
Solution:
We have AB = AC â‡’ âˆ  B = âˆ  C          [âˆµ Angles opposite to equal sides are equal]
âˆ´ âˆ A + âˆ B + âˆ C = 180Â°
â‡’ âˆ A + âˆ B + âˆ B = 180Â°
â‡’ âˆ A + 2âˆ B = 180Â°
â‡’ 80Â° + 2âˆ B = 180Â°
â‡’ 2âˆ B = 180Â°- 80Â°
= 100
â‡’ âˆ B= (100o/2) = 50Â°

Question 8. Find the measure of each of acute angle in a right angle isosceles triangle.
Solution:
Let the measure of each of the equal acute angle of the Î” be x
âˆ´ We have: x + x + 90Â° = 180Â°
â‡’ x + x = 180Â° - 90Â° = 90Â°
â‡’ x= (90o/2)= 45Â°

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