This is the concept of geometry, to solve for the long base of the parallelogram we use sine rule which states that, given triangle ABC with sides a,b and c
then
a/sin A=b/sin B=c/sin C
From our question, ABC=130, thus b=18 in
BAC=30, the length of the base will be a
thus;
a/sin 30=18/sin 130
a=(18sin 30)/sin 130
a=9/0.7660
a=11.75 inches
The base is therefore 11.75 inches
