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How would you reason this and find out the size

 Nov 7, 2018
 #1
avatar+21 
+2

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

 Nov 7, 2018
 #2
avatar+98044 
+2

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° 

 

 

 

cool cool cool

 Nov 7, 2018

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