Get reliable answers to your questions at Westonci.ca, where our knowledgeable community is always ready to help. Join our platform to connect with experts ready to provide detailed answers to your questions in various areas. Get precise and detailed answers to your questions from a knowledgeable community of experts on our Q&A platform.

A surveyor is trying to determine the distance between points [tex]\(X\)[/tex] and [tex]\(Z\)[/tex]. However, the distance cannot be determined directly as a ridge lies between the two points. From a point [tex]\(Y\)[/tex] which is equidistant from [tex]\(X\)[/tex] and [tex]\(Z\)[/tex], he measures the angle [tex]\(\angle XYZ\)[/tex].

a) If [tex]\(XY = x\)[/tex] and [tex]\(\angle XYZ = \theta\)[/tex], show that [tex]\(XZ = x \sqrt{2(1 - \cos \theta)}\)[/tex].

b) Calculate [tex]\(XZ\)[/tex] (to the nearest kilometre) if [tex]\(x = 240 \, \text{km}\)[/tex] and [tex]\(\theta = 132^\circ\)[/tex].


Sagot :

Let's tackle the problem presented by the surveyor step-by-step.

## Part (a):
We start with point [tex]\(Y\)[/tex] being equidistant from points [tex]\(X\)[/tex] and [tex]\(Z\)[/tex], therefore [tex]\(XY = YZ = x\)[/tex].

The problem requires us to find [tex]\(XZ\)[/tex] in terms of [tex]\(x\)[/tex] and [tex]\(\theta\)[/tex].

To solve this, we will use the Law of Cosines, which states:
[tex]\[ c^2 = a^2 + b^2 - 2ab\cos(\theta) \][/tex]

In this scenario:
- [tex]\(a = XY = x\)[/tex]
- [tex]\(b = YZ = x\)[/tex]
- [tex]\(\theta = \angle XYZ\)[/tex]
- [tex]\(c = XZ\)[/tex]

Plugging these values into the Law of Cosines, we get:
[tex]\[ XZ^2 = XY^2 + YZ^2 - 2 \cdot XY \cdot YZ \cdot \cos(\theta) \][/tex]

Substituting [tex]\(XY = x\)[/tex] and [tex]\(YZ = x\)[/tex]:
[tex]\[ XZ^2 = x^2 + x^2 - 2 \cdot x \cdot x \cdot \cos(\theta) \][/tex]

Simplify the equation:
[tex]\[ XZ^2 = 2x^2 - 2x^2 \cos(\theta) \][/tex]
[tex]\[ XZ^2 = 2x^2 (1 - \cos(\theta)) \][/tex]

Taking the square root on both sides to solve for [tex]\(XZ\)[/tex]:
[tex]\[ XZ = \sqrt{2x^2(1 - \cos(\theta))} \][/tex]
[tex]\[ XZ = x \sqrt{2(1 - \cos(\theta))} \][/tex]

Hence, we have shown that:
[tex]\[ XZ = x \sqrt{2(1 - \cos(\theta))} \][/tex]

## Part (b):
Now, we need to calculate [tex]\(XZ\)[/tex] if [tex]\(x = 240 \, \text{km}\)[/tex] and [tex]\(\theta = 132^\circ\)[/tex].

### Step-by-step Calculation:
1. Convert [tex]\(\theta\)[/tex] from degrees to radians:
[tex]\[ \theta = 132^\circ \][/tex]
The conversion formula is [tex]\( \theta \text{ radians} = \theta \text{ degrees} \times \left(\frac{\pi}{180}\right) \)[/tex]:
[tex]\[ \theta = 132 \times \left(\frac{\pi}{180}\right) \approx 2.303 \text{ radians} \][/tex]

2. Calculate [tex]\(\cos(\theta)\)[/tex]:
[tex]\[ \cos(132^\circ) = \cos(2.303 \text{ radians}) \approx -0.669 \][/tex]

3. Plug these values into the formula [tex]\(XZ = x \sqrt{2(1 - \cos(\theta))}\)[/tex]:
[tex]\[ XZ = 240 \, \text{km} \times \sqrt{2(1 - (-0.669))} \][/tex]
[tex]\[ XZ = 240 \times \sqrt{2(1 + 0.669)} \][/tex]
[tex]\[ XZ = 240 \times \sqrt{2(1.669)} \][/tex]
[tex]\[ XZ = 240 \times \sqrt{3.338} \][/tex]
[tex]\[ XZ \approx 240 \times 1.827 \][/tex]
[tex]\[ XZ \approx 438.48 \][/tex]

4. Rounding to the nearest kilometer:
[tex]\[ XZ \approx 439 \, \text{km} \][/tex]

Therefore, the distance between points [tex]\(X\)[/tex] and [tex]\(Z\)[/tex] is approximately [tex]\(439\)[/tex] kilometers.