Question 1062184

Since angles look the same every 360 degrees, we can add and/or subtract 360 to get the argument of the tan() function into range (or, a good calculator will automatically do this for you, make sure you have it set to "deg" mode):
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tan(-405) = tan(-405+360) = tan(-45) = -1
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By convention, angles are measured as a rotation from the positive x-axis with counterclockwise rotations considered to be positive angles.