Page 49 - Mathematics Class - IX

Viva-Voce

1. What is congruency? Is it same as similarity?
Ans. When any two polygons are same in shape and size, i.e. all corresponding sides and all angles are equal, it
is said to be congruent.
Whereas similarity means corresponding angles are same but corresponding sides are in proportion.
2. What does ‘c.p.c.t.’ stands for?

Ans. It stands for corresponding parts of congruent triangles.
3. Name the four valid conditions of congruency for two triangles.
Ans. The conditions are SSS, SAS, ASA and RHS.
4. Are all equilateral triangles congruent? Why?
Ans. No, because the sides may or may not be equal.

5. Are the two triangles made by the diagonal of a parallelogram congruent?
Ans. Yes, the two triangles are congruent.

MCQs

1. In ∆ABC and ∆PQR, AB = QP, ∠B = ∠P and BC = PR. What congruency condition does it satisfy?
a) ASA b) SSS c) SAS d) RHS

2. In ∆ABC, AB = AC and AD ^ BC. Which of the following will be true?
a) ∆ADB ≅ ∆ACD b) ∆ADC ≅ ∆ADB c) ∆BAD ≅ ∆DCA d) None of these

3. In the given figure, ∠ABD : ∠ACD is
a) 1 : 1 b) 2 : 1 c) 1 : 2 d) 2 : 3

A

D

B C
4. Which one of the congruency conditions is not true?
a) SSS b) SSA c) RHS d) AAS

5. All congruent triangles are
a) not similar b) equal in area

c) equal in size but not shape d) none of these

Answers: 1. c) SAS 2. b) ∆ADC ≅ ∆ADB 3. a) 1 : 1

4. b) SSA 5. b) equal in area

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