Answer:
Applying cosine theorem:
AB = sqrt(AC^2 + BC^2 - 2 x AB x BC x cosC)
= sqrt( 72^2 + 135^2 - 2 x 72 x 135 x cos(119deg))
= 181
Applying sine theorem:
BC/sinA = AB/sinC
=> sinA = BC x sinC/AB
=> A = arcsin(BC x sinC/AB)
= arcsin( 135 x sin(119deg)/181)
= 40.7 deg
Hope this helps!
:)
