The problem asks us to find the exact values of $\sec(\frac{3\pi}{4})$ and $\cot(\frac{-11\pi}{6})$.

TrigonometryTrigonometryTrigonometric FunctionsSecantCotangentUnit CircleAngle ConversionSpecial Angles
2025/3/13

1. Problem Description

The problem asks us to find the exact values of sec(3π4)\sec(\frac{3\pi}{4}) and cot(11π6)\cot(\frac{-11\pi}{6}).

2. Solution Steps

10) We want to evaluate sec(3π4)\sec(\frac{3\pi}{4}). Recall that sec(x)=1cos(x)\sec(x) = \frac{1}{\cos(x)}.
First, we determine cos(3π4)\cos(\frac{3\pi}{4}).
The angle 3π4\frac{3\pi}{4} is in the second quadrant. The reference angle is π3π4=π4\pi - \frac{3\pi}{4} = \frac{\pi}{4}.
In the second quadrant, cosine is negative. Thus, cos(3π4)=cos(π4)=22\cos(\frac{3\pi}{4}) = -\cos(\frac{\pi}{4}) = -\frac{\sqrt{2}}{2}.
Then, sec(3π4)=1cos(3π4)=122=22=222=2\sec(\frac{3\pi}{4}) = \frac{1}{\cos(\frac{3\pi}{4})} = \frac{1}{-\frac{\sqrt{2}}{2}} = -\frac{2}{\sqrt{2}} = -\frac{2\sqrt{2}}{2} = -\sqrt{2}.
11) We want to evaluate cot(11π6)\cot(\frac{-11\pi}{6}). Recall that cot(x)=cos(x)sin(x)\cot(x) = \frac{\cos(x)}{\sin(x)}.
Also, cot(x)=cot(x)\cot(-x) = -\cot(x).
The angle 11π6\frac{-11\pi}{6} is coterminal with 11π6+2π=11π6+12π6=π6\frac{-11\pi}{6} + 2\pi = \frac{-11\pi}{6} + \frac{12\pi}{6} = \frac{\pi}{6}.
Thus, cot(11π6)=cot(π6)\cot(\frac{-11\pi}{6}) = \cot(\frac{\pi}{6}).
We know that cos(π6)=32\cos(\frac{\pi}{6}) = \frac{\sqrt{3}}{2} and sin(π6)=12\sin(\frac{\pi}{6}) = \frac{1}{2}.
Therefore, cot(π6)=cos(π6)sin(π6)=3212=3221=3\cot(\frac{\pi}{6}) = \frac{\cos(\frac{\pi}{6})}{\sin(\frac{\pi}{6})} = \frac{\frac{\sqrt{3}}{2}}{\frac{1}{2}} = \frac{\sqrt{3}}{2} \cdot \frac{2}{1} = \sqrt{3}.

3. Final Answer

10) 2-\sqrt{2}
11) 3\sqrt{3}

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