1. State the problem (Question 17):
Given the terminal point for angle $\theta$ is $(-4,-7)$, find the values of the six trigonometric functions: $\sin\theta,\cos\theta,\tan\theta,\csc\theta,\sec\theta,\cot\theta$.
2. Use the key triangle/coordinate relationships:
Let the terminal point be $(x,y)$ and $r=\sqrt{x^2+y^2}$.
Then:
$\sin\theta=\frac{y}{r}$
$\cos\theta=\frac{x}{r}$
$\tan\theta=\frac{y}{x}$
$\csc\theta=\frac{r}{y}$
$\sec\theta=\frac{r}{x}$
$\cot\theta=\frac{x}{y}$
3. Identify $x$, $y$, and compute $r$:
$x=-4$
y=-7$
$$r=\sqrt{(-4)^2+(-7)^2}=\sqrt{16+49}=\sqrt{65}$$
4. Compute $\sin\theta$:
$\sin\theta=\frac{y}{r}=\frac{-7}{\sqrt{65}}$
5. Compute $\cos\theta$:
$\cos\theta=\frac{x}{r}=\frac{-4}{\sqrt{65}}$
6. Compute $\tan\theta$:
$\tan\theta=\frac{y}{x}=\frac{-7}{-4}$
$\tan\theta=\cancel{(-7)}\div\cancel{(-4)}=\frac{7}{4}$
7. Compute $\csc\theta$:
$\csc\theta=\frac{r}{y}=\frac{\sqrt{65}}{-7}$
8. Compute $\sec\theta$:
$\sec\theta=\frac{r}{x}=\frac{\sqrt{65}}{-4}$
9. Compute $\cot\theta$:
$\cot\theta=\frac{x}{y}=\frac{-4}{-7}$
$\cot\theta=\cancel{(-4)}\div\cancel{(-7)}=\frac{4}{7}$
10. Final answers for Question 17:
$\sin\theta=\frac{-7}{\sqrt{65}}$
$\cos\theta=\frac{-4}{\sqrt{65}}$
$\tan\theta=\frac{7}{4}$
$\csc\theta=\frac{-\sqrt{65}}{7}$
$\sec\theta=\frac{-\sqrt{65}}{4}$
$\cot\theta=\frac{4}{7}$
Trigonometry At Point 2Db2A3
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