Making a drawing first and taking a question in visually often helps to avoid long calculations and associated with them mistakes.
The origin - point O (0, 0).
AO = BO = 2 ==> triangle AOB is isosceles,
Perpendicular to the middle of its base AB is also a bisector of <AOB.
In other words, L is a line of symmetry for AOB.
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http://regentsprep.org/Regents/math/...ry/Lsymmet.htm .
Line L is a bisector of the first quadrant, and its equation is
y = x,
so all the points on line L have equal coordinates of type (n, n).
Answer D (3, 3) is the correct one.
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RE: overlapping.
How many nonoverlapping triangles are formed in a square when its diagonals are drawn?
Four.
Now, how many triangles are formed in a square when its diagonals are drawn?