Triangle Books Bearing
1. **Problem 1: Express $x$ in the form $a + b\sqrt{c}$**
Given a right triangle with hypotenuse $x + 16$, one leg $2x$, and the angle opposite the leg $2x$ is $30^\circ$.
2. Use the sine definition: $\sin 30^\circ = \frac{\text{opposite}}{\text{hypotenuse}} = \frac{2x}{x+16}$.
3. Since $\sin 30^\circ = \frac{1}{2}$, set up the equation:
$$\frac{1}{2} = \frac{2x}{x+16}$$
4. Cross-multiply:
$$x + 16 = 4x$$
5. Rearrange:
$$16 = 3x \implies x = \frac{16}{3}$$
6. Check if $x$ can be expressed as $a + b\sqrt{c}$ with integers $a,b,c$. Here, $x = \frac{16}{3}$ is a rational number, so $a=\frac{16}{3}$, $b=0$, $c=0$.
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1. **Problem 2: Total books read by the youth group**
- Number of girls = 11, mean books per girl = 8
- Number of boys = 7, mean books per boy = 4
2. Total books by girls:
$$11 \times 8 = 88$$
3. Total books by boys:
$$7 \times 4 = 28$$
4. Total books by youth group:
$$88 + 28 = 116$$
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1. **Problem 3: Bearing from A to B**
- Coordinates: $A(1,3)$, $B(8,7)$
2. Calculate differences:
$$\Delta x = 8 - 1 = 7$$
$$\Delta y = 7 - 3 = 4$$
3. Calculate angle $\theta$ from north clockwise:
- Bearing is measured clockwise from north.
- Calculate angle from east axis:
$$\alpha = \arctan\left(\frac{\Delta y}{\Delta x}\right) = \arctan\left(\frac{4}{7}\right) \approx 29.74^\circ$$
4. Bearing from north:
$$\text{bearing} = 90^\circ - \alpha = 90^\circ - 29.74^\circ = 60.26^\circ$$
5. Rounded to nearest degree:
$$60^\circ$$
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**Final answers:**
- Problem 1: $a = \frac{16}{3}$, $b = 0$, $c = 0$
- Problem 2: Total books = 116
- Problem 3: Bearing from A to B = $60^\circ$