Let be the three angles of a triangle in A.P. with d>0
Since the sum of the angles of a triangle is
∴
Now, number of degrees in the least angle = (60 - d)
Number of degrees in the greatest angle = (60 + d)
Number of radians in the greatest angle =
According to the given condition,
4d = 120 d = 30
Hence, the angles of a triangle in degrees are:
or