Sina /a = Sina /b

Sina = asinb/b = 20x0.5/1= 0.90909, a = 65, or a =180-65 =115.

C = 180-30-65 = 85 or c =180-30-115 = 35.

C = BSINC/SINB =11sin85/sin30 = 22cm or c =11sin35/sin30 =13cm.

Two solutions:

A=65，B=30，C=85，a=20，b= 1 1，c=22

A= 1 15，B=30，C=35，a=20，b= 1 1，c= 13

(2) Sine theorem

sinB = bsinC/c = 39 sin 1 15/54 = 0.6546，

B=4 1

a = 180-4 1- 1 15 = 24

a = csinA/sinC = 54 sin 24/sin 1 15 = 24cm

A=24，B=4 1，C= 1 15，a=24，b=39，c=54