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Congruency of Triangles > Exercise 8.1

Exercise 8.1

1. Decide whether the SSS congruence is true with the following figures. Give reasons

Solution:

(i)

Let's check if SSS congruence criterion is satisfied:

Given triangles ∆NBE and ∆ARC have:

AC = BR (marked with parallel lines)

CR = NB (marked with parallel lines)

AR and NE are not marked

Since all three pairs of sides are not equal:

SSS congruence is

Therefore, ∆NBE is not to ∆ARC

(ii)

Let's check if SSS congruence criterion is satisfied:

Given triangles ∆LSD and ∆LAD have:

LA =

LS ≠

LD = (common side)

Since all three pairs of sides are not equal: SSS congruence is

Therefore, ∆LSD congruent to ∆LAD

For the following congruent triangles, find the pairs of corresponding angles.

Solution:

(i)

Let's find the corresponding angles in congruent triangles:

Given ∆PTQ and ∆RSQ are congruent with:

PQ =

PT =

QT =

∠P = ∠

∠TQP = ∠

∠T = ∠

(ii)

Let's find the corresponding angles in congruent triangles:

Given ∆POQ and ∆ROS are congruent with:

PO =

OQ =

PQ =

∠ROS = ∠

∠R = ∠

∠S = ∠

3. In adjacent figure, choose the correct answer!

Solution:

Let's determine which option is correct:

Given quadrilateral PQRS with:

PR = SQ = cm

PQ is to both triangles

PS = RQ = cm

Since all corresponding sides are equal:

Option is correct: ∆PQR ≅ ∆PQS

Therefore, ΔPQR ≅ ΔPQS by SSS criterion

4. In the figure given below, AB = DC and AC = DB. Is ΔABC ≅ ΔDCB.

Solution:

Let's check if the triangles are congruent:

Given that:

AB =

AC =

Comparing ∆ABC and ∆DCB: AB = (given)

BC is to both triangles

AC = (given)

Since all three pairs of sides are equal: ∆ABC ≅ ∆DCB by SSS criterion