Circle theorem

well... this triangle i beleive has a right angle and thats 90 degrease and since you are missing a number and the numbers in a triangle always add up to 180 just add 28 and 90 and whatever the answer is subtract that from 180 and that how you get the missing number *remember that there is a right angle thats why there is only one missing number . i only know that one.. i think thats right

Thanks, ILP......!!!!

Angle OAD  is a right angle

So....Angle AOD is complementary to Angle OAD  =  90 - 28  = 62°  = Angle AOC

Note that Angle AOC is a central angle intercepting minor  arc CA

And Angle ABC  is an inscribed angle intercepting minor arc CA....so it has 1/2 the measure of AOD  =  (1/2) (62)  =  31°