You can
put this solution on YOUR website!The tangent function is defined as:
Tan(θ)=Sin(θ)/Cos(θ)
Now, what can we not divide by in the system of real numbers? Correct, 0.
So Cos(θ) cannot equal zero. This occurs at 90 degrees and 270 degrees. (The x value is zero on the unit circle.) In radians,

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