Which of the following lines, when drawn together with the -axis and the -axis, encloses an isosceles triangle?
Solution
Since the triangle will include the two axes, then the triangle will have a right angle. For the triangle to be isosceles, the other two angles must be . For a line to make an angle of with both axes, it must have slope 1 or -1. Of the given possibilities, the only such line is .
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