A) 1:2:3 - Let these angles equal x, 2x & 3x.
By angle sum property of a triangle,
x+2x+3x = 6x = 180.
So, x = 30 & 2x =60 & 3x = 90. Hence, it is the ratio of angles in a right-angled triangle.
B) 1:1:2 - Let these angles equal x, x & 2x.
By angle sum property of a triangle,
x+x+2x = 4x = 180.
So, x = 45 & x =45 & 2x = 90. Hence, it is the ratio of angles in a right-angled triangle.
C) 1:3:6 - Let these angles equal x, 3x & 6x.
By angle sum property of a triangle,
x+3x+6x = 10x = 180.
So, x = 18 & 3x =54 & 6x = 108. Hence, it is not the ratio of angles in a right-angled triangle.
Option C is the Correct Answer.