![Requested Picture cannot be found](ReferenceAngleQuadrant3.jpg) | The reference angle for an angle in quadrant 3 is equal to the angle minus 180 degrees.
In this case, the angle is 225 degrees and the reference angle is 225 - 180 = 45 degrees.
The trigonometric functions of 225 degrees are the same as the trigonometric functions of 45 degrees except for the signs.
Sin(225) = -Sin(45) = -.707106781 Cos(225) = -Cos(45) = -.707106781 Tan(135) = Tan(45) = 1
The sine function is negative because the opposite side is below the x-axis.
The cosine function is negative because the adjacent side is to the left of the y-axis.
The tangent function is positive because it is equal to the opposite side divided by the adjacent side and a negative divided by a negative is positive.
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