we know that
the law of cosines establish
c²=a²+b²-2*a*b*cos C------> cos C=[a²+b²-c²]/[2*a*b]
in this problem
a=11 units
b=11 units
c=14 units
C=angle A
cos C=[11²+11²-14²]/[2*11*11]-----> cos C=0.19008
C=arc cos (0.19008)------> C=79.04°
the answer is
the measure of angle A is 79°
