The measures of the three angles of a triangle form an arithmetic sequence. What must be the measure, in degrees, of at least one of its angles?
Let the three angles be a1, a1 + d and a1 + 2d
So....we have that
a1 + (a1 + d) + (a1 + 2d) = 180°
3a1 + 3d = 180° divide through by 3
(a1 + d) = 60°
So......one of the angles must be 60°
Thank you so much!
+1452 
