Area Tan
1. **State the problem:** We are given the function $y = \tan(x)$ and a region $R$ bounded by the curve $y = \tan(x)$, the x-axis, and the vertical line $x = \frac{\pi}{6}$. We want to approximate the area of $R$ using the trapezium rule with the given table values, then find the exact area by integration, and finally calculate the percentage error.
2. **Given data:**
\begin{align*}
x &: 0, \frac{\pi}{24}, \frac{\pi}{12}, \frac{3\pi}{24}, \frac{\pi}{6} \\
y &: 0, \text{Box 1}, \text{Box 2}, \text{Box 3}, 0.577
\end{align*}
We know $y = \tan(x)$, so calculate the missing values:
\begin{align*}
\tan\left(\frac{\pi}{24}\right) &= \tan(7.5^\circ) \approx 0.132 \\
\tan\left(\frac{\pi}{12}\right) &= \tan(15^\circ) \approx 0.268 \\
\tan\left(\frac{3\pi}{24}\right) &= \tan(22.5^\circ) \approx 0.414
\end{align*}
3. **Apply the trapezium rule:**
The trapezium rule for $n$ intervals with points $x_0, x_1, ..., x_n$ and function values $y_0, y_1, ..., y_n$ is:
$$\text{Area} \approx \frac{h}{2} \left(y_0 + 2\sum_{i=1}^{n-1} y_i + y_n\right)$$
where $h$ is the width of each subinterval.
Here, $h = \frac{\pi}{24}$ and $n=4$ intervals.
Calculate:
$$\text{Area} \approx \frac{\pi/24}{2} \left(0 + 2(0.132 + 0.268 + 0.414) + 0.577\right)$$
Sum inside parentheses:
$$2(0.132 + 0.268 + 0.414) = 2(0.814) = 1.628$$
Total:
$$0 + 1.628 + 0.577 = 2.205$$
So area approximation:
$$\text{Area} \approx \frac{\pi}{48} \times 2.205 \approx 0.1445 \times 2.205 = 0.318$$
4. **Exact area by integration:**
The exact area under $y = \tan(x)$ from $0$ to $\frac{\pi}{6}$ is:
$$\int_0^{\pi/6} \tan(x) \, dx$$
Recall:
$$\int \tan(x) \, dx = -\ln|\cos(x)| + C$$
Evaluate:
$$\int_0^{\pi/6} \tan(x) \, dx = [-\ln|\cos(x)|]_0^{\pi/6} = -\ln\left(\cos\frac{\pi}{6}\right) + \ln(\cos 0)$$
Calculate values:
$$\cos\frac{\pi}{6} = \frac{\sqrt{3}}{2} \approx 0.866, \quad \cos 0 = 1$$
So:
$$= -\ln(0.866) + \ln(1) = -(-0.1447) + 0 = 0.1447$$
Rounded to 3 decimal places:
$$0.145$$
5. **Percentage error:**
$$\text{Percentage error} = \left|\frac{\text{Approximate} - \text{Exact}}{\text{Exact}}\right| \times 100 = \left|\frac{0.318 - 0.145}{0.145}\right| \times 100 = 119\%$$
Rounded to nearest integer: 119%
**Final answers:**
- Approximate area (trapezium rule): $0.318$
- Exact area (integration): $0.145$
- Percentage error: $119\%$