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YZ = MN
and XZ = LN
which is the RHS criterion of right triangles for congruency.

Observation
By actual measurement,

1. In the pair of ΔABC and ΔDEF,
AB = DE = ……… , BC = EF = ……… , AC = DF = ……… ,
∠A = ……… , ∠B = ……… ,
∠C = ……… , ∠D = ……… ,
∠E = ……… , ∠F = ……… .
Hence, ΔABC ≅ ΔDEF
2. In the pair of ΔGFII and ΔJKL,
GH =JK = ……… , Gl = JL = ……… ,
HI = ……… , KL = ……… ,
∠G = ……… , ∠J = ……… ,
∠H = ……… , ∠K = ……… ,
∠l= ……… , ∠L = ……… ,
Hence, ΔGHI ≅ ΔJKL
3. In the pair of ΔPQR and ΔSTU,
QR = TU = ……… , PQ = ……… ,
ST = ……… , PR = ……… ,
SU = ……… , ∠S = ……… ,
∠Q = ∠T= ……… , ∠R = ∠U = ……… ,
∠P = ……… .
Hence, ΔPQR ≅ ΔSTU
4. In the pair of ΔXYZ and ΔLMN, hypotenuse YZ = hypotenuse MN = ………. ,
XZ = LN =……… , XY = ……… ,
LM = ……… , ∠X = ∠L = ……… ,
∠Y= ……… , ∠M = ……… ,
∠Z = ……… , ∠N = ……… .
Hence, ΔXYZ ≅ ΔLMN

Result
Using triangle cut outs, we have verified experimentally the different criteria for congruence of
triangles.

Application
These criteria are useful in

1. Solving many problems in geometry.
2. Practical problems such as finding width of a river without crossing it.

Viva Voce
Question 1:
What do you understand by congruent figures?
Answer:
Two figures are congruent, if they are of the same shape and same size.