#6**+1 **

Since AD = DC....then angles CAD and ACD are equal

And angle ACD = 40 = angle CAD

So....angle CDA = 180 - 40 - 40 = 100

So angle ADB = 180 - 100 = 80

And BD = BA.....so angles BAD and ABD are equal

So angle BAD = [ 180 - angle ADB ] / 2 = [ 180 - 80] / 2 = 100/ 2 = 50

So angle BAC = angle CAD + angle BAD = 40 + 50 = 90°

CPhill Feb 24, 2019