Respuesta :

Side CB is the same as AD.
Side AB is the same as CD.
<CAD is 15 degrees
<ACD is 24 degrees
now use a^2 +b^2=c^2 to find the last angle
As its given, this is a parallogram Side AB = 12
Side BC = 13

Angle CAD = 15
Angle ACD = 24

Sum of all angle in triangle = 180
Angle ADC = 180 - 15 -24 = 141
Angle ABC = 141