Find the angle between the ray OA and the positive semiaxis Ox? if point A (-3; 3).

OB = 3 cm, AB = OС = 3 cm.

Triangle ОАВ is rectangular, then tgАВ = AB / ОВ = 3/3 = 1.

angle AOB = arctg1 = 45.

Then the angle α = 180 – 45 = 135

Answer: The angle between OA and the positive OX semiaxis is 135.

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