The pole casts a 12-foot shadow when the sun is at a [tex]40^{\circ}[/tex] angle of elevation. Which equation could Kim use to find [tex]x[/tex], the length of the pole?

A. [tex]\frac{\sin 40}{x} = \frac{\sin 60}{12}[/tex]
B. [tex]\frac{\sin 40}{12} = \frac{\sin 60}{x}[/tex]
C. [tex]\frac{\sin 60}{x} = \frac{\sin 80}{12}[/tex]
D. [tex]\frac{\sin 80}{x} = \frac{\sin 40}{12}[/tex]



Answer :

Alright, let's go through the problem step by step.

1. Understanding the problem:
- We are given a pole that casts a 12-foot shadow.
- The sun's angle of elevation is \(40^\circ\).
- We need to find the equation that can help us determine \(x\), which is the length of the pole.

2. Identifying the right trigonometric function:
- In this problem, we are dealing with angles and the lengths of sides in a right triangle formed by the pole, its shadow, and the line of sight from the top of the pole to the tip of the shadow.

3. Using the Sine Law:
- The Sine Law states:
[tex]\[ \frac{\sin A}{a} = \frac{\sin B}{b} \][/tex]
for any triangle, where \(A\) and \(B\) are angles, and \(a\) and \(b\) are the sides opposite those angles respectively.

4. Applying the given values:
- In the given problem, we need an equation to relate the angle of elevation, the shadow length, and the pole's height.

5. Choosing the correct equation:
- We need to identify which of the given equations appropriately uses the Sine Law to solve for \(x\) (the length of the pole):
- \(\frac{\sin 40}{x} = \frac{\sin 60}{12}\)
- \(\frac{\sin 40}{12} = \frac{\sin 60}{x}\)
- \(\frac{\sin 60}{x} = \frac{\sin 80}{12}\)
- \(\frac{\sin 80}{x} = \frac{\sin 40}{12}\)

6. Comparing the options:
- We are working with \(\sin 40^\circ\), \(\sin 60^\circ\), and the known length of the shadow \(12\), to find the height \(x\).
- Match given values with appropriate form:
[tex]\[ \frac{\sin 40}{12} = \frac{\sin 60}{x} \][/tex]

This equation appropriately uses the Sine Law to relate the angle of elevation \(40^\circ\), the known length of shadow (12 feet), and another angle of \(60^\circ\) with the unknown length \(x\).

So, the correct equation that Kim could use to find \(x\), the length of the pole, is:
[tex]\[ \boxed{\frac{\sin 40}{12}=\frac{\sin 60}{x}} \][/tex]

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