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.

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**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= (100

**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= (90

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