https://www.gregmat.com/problems/quant?problem=the-angle-between-the-line
hey hi! I’m not sure I entirely understand the explanation. How did you ascertain that this a reflection across y=x? I suppose I see the logic of the triangles that you drew now, but please could you clarify the reflection idea? That’s 45 degrees isn’t it
Blue line makes 30° with x-axis
Red line makes 45° with x-axis aka line y=x
Green line makes 60° with x-axis
Angle between y-axis and green is 30°
Angle between between green and blue lines is 30°
Notice how redline sits exactly in the middle and therefore acts as a mirror reflecting the points on Blue and green equally.
The points therefore swap as shown here Reflection across a line
