ML AGGARWAL CLASS 7 Chapter 12 Congruence of Triangles Exercise 12.1

  Exercise 12.1


Question 1

$\begin{array}{ll}A B=F E & \angle A=\angle F \\ B C=E D & \angle B=\angle E \\ A C=F D & \angle C=\angle D\end{array}$

Question 2

(i)$\angle C$

(ii)$\overline{C A}$

(iii)$\angle A$

(iv)$\overline{B A}$

Question 3

(i) $\overline{B C}=\overline{P R}$

$\overline{A B}=$ $\overline{Qp}$

$\overline{A C}=\overline{Q R}$

∴ By using SSS  Congruence Rule 

$\triangle A B C \cong \triangle Q P R$

(ii) $\overline{Q R} \neq \overline{A B}$

$\overline{PR}=\overline{A C}$

$\overline{PQ}=B C$

As one side is not equal both are not congruent

Question 4

(i) In $\triangle A B D, \triangle A C D$

$\overline{A B}=\overline{A C}$

$\overline{A D}=\overline{A D}$

$\overline{B D}=\overline{C D}$


(ii) By sss triangle congruency

$\triangle A B D \cong \triangle A D C$
(i) $\overlin

(iii) $\angle B=\angle C$ (∵Corresponding congruent parts)

Question 5

{A B}=\overline{A C}$

$\overline{A D}=\overline{A D}$

$\overline{B D}=\overline{C D}$ (∵D is mid point of BC)

(ii) By SSS triangle congruency 

$\triangle A D B \cong \triangle A D C$

(iii) $\angle B=\angle C$ (∵Corresponding congruent parts)

Question 6

(i) $\overline{A B}=\overline{D E}$

$\overline{A C}=\overline{D F}$

$\angle A \neq \angle D$
 
∴ Triangle are not congruent 

(ii) $\overline{A C}=\overline{R P}$

$\overline{B C}=\overline{Q O}$

$\angle C=\angle P$

By SAS congruency 

$\triangle A B C \cong \triangle R Q P$

(iii) $\overline{D F}=\overline{P Q}$

$\overline{E F}=\overline{R Q}$

$\angle F=\angle Q$

By SAS Congruency 

$\triangle D E F \cong \triangle P R Q$

(iv)$\overline{A B}=\overline{P Q}$

$\overline{B C}=\overline{Q R}$

$\angle B=\angle R=80^{\circ}$(but they are not congruent part)

So given , triangle are not congruent

Question 7

$\angle P=\angle F$

Question 8

(a) (i) $A R=P E$

(ii) $\rangle R T=E N$

(iii)AT =P N

(b) (i) $R T=E N$

(ii) $P N=A T$

Question 9

(i) Given 

(ii) Given 

 (iii) Common side

 (iv) SAS rule of congruency 

Question 10

(i) $\overline{R S}=\overline{P Q}$

$\angle R=\angle P$

$\overline{D R}=\overline{R P}$
 
(ii) By SAS congruency 

$\triangle P S R \cong \triangle R O P$

(iii) Yes, congruent parts

(iv) Yes, congruent parts

Question 11

(i) $\overline{A B}=\overline{D C}$

$\angle B=\angle C$

$\overline{B C}=\overline{C B}$

(ii) Yes, By SAS congruency of triangle 

(iii) Yes, congruent parts are equal

Question 12

(i) $\overline{A C}=\overline{A D}$

$\angle A=\angle A$

$\overline{A B}=\overline{A B}$

(ii) Yes, $\triangle A B C \cong \triangle A B D$ , by SAS congruency 

(iii) Yes, congruent parts 

(iv) yes , congruent parts

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