In Fig. 10.135, the measure of ∠B’AC’ is
In 
ABC and 
A'B'C',
AB= A'B' (Given)
∠B = ∠B'(Given)
BC = B'C' (Given)
Hence, by S.A.S. theorem,
ABC 
A'B'C'
Therefore,
By c.p.c.t
∠A = ∠A'
3x = 2x +20
x = 20°
Therefore angle A' = 2x +20
= 60°
12
In Fig. 10.135, the measure of ∠B’AC’ is
In ABC and A'B'C',
AB= A'B' (Given)
∠B = ∠B'(Given)
BC = B'C' (Given)
Hence, by S.A.S. theorem,
ABC A'B'C'
Therefore,
By c.p.c.t
∠A = ∠A'
3x = 2x +20
x = 20°
Therefore angle A' = 2x +20
= 60°