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Introduction

Trigonometric equations are a fundamental part of mathematics, and solving them is a crucial skill for students and professionals alike. In this article, we will focus on solving a specific type of trigonometric equation involving the cosine function. We will find all angles θ\theta between 00^{\circ} and 180180^{\circ} that satisfy the given equation.

The Equation

The equation we will be solving is:

cos(θ)=12\cos (\theta) = \frac{1}{2}

This equation involves the cosine function, which is a periodic function that oscillates between -1 and 1. The cosine function is defined as the ratio of the adjacent side to the hypotenuse in a right-angled triangle.

Understanding the Cosine Function

Before we proceed to solve the equation, let's take a closer look at the cosine function. The cosine function has a period of 360360^{\circ}, which means that it repeats itself every 360360^{\circ}. The cosine function is also an even function, which means that cos(θ)=cos(θ)\cos (-\theta) = \cos (\theta).

Solving the Equation

To solve the equation cos(θ)=12\cos (\theta) = \frac{1}{2}, we need to find all angles θ\theta between 00^{\circ} and 180180^{\circ} that satisfy this equation. We can start by finding the reference angle, which is the acute angle between the terminal side of the angle and the x-axis.

Finding the Reference Angle

The reference angle for cos(θ)=12\cos (\theta) = \frac{1}{2} is 6060^{\circ}, since cos(60)=12\cos (60^{\circ}) = \frac{1}{2}. This means that the angle θ\theta is either 6060^{\circ} or 120120^{\circ}.

Finding the Angles in the Given Range

Since we are looking for angles between 00^{\circ} and 180180^{\circ}, we can conclude that the only angle that satisfies the equation is θ=60\theta = 60^{\circ}.

Rounding the Answer

We are asked to round our answer to one decimal place. Since 6060^{\circ} is already an integer, we can conclude that the rounded answer is still 6060^{\circ}.

Conclusion

In this article, we solved a trigonometric equation involving the cosine function. We found that the only angle between 00^{\circ} and 180180^{\circ} that satisfies the equation is θ=60\theta = 60^{\circ}. We also rounded our answer to one decimal place, which is still 6060^{\circ}.

Final Answer

The final answer is 60.0\boxed{60.0}.

Additional Information

If you want to find the angles in the range 00^{\circ} to 360360^{\circ}, you can use the following formula:

θ=cos1(12)+360k\theta = \cos^{-1} \left( \frac{1}{2} \right) + 360^{\circ} k

where kk is an integer. This will give you all the angles in the range 00^{\circ} to 360360^{\circ} that satisfy the equation.

Example Use Case

Suppose you want to find the angles in the range 00^{\circ} to 360360^{\circ} that satisfy the equation cos(θ)=12\cos (\theta) = \frac{1}{2}. You can use the formula above to find the angles:

θ=cos1(12)+360k\theta = \cos^{-1} \left( \frac{1}{2} \right) + 360^{\circ} k

where kk is an integer. Plugging in k=0k = 0, you get:

θ=cos1(12)\theta = \cos^{-1} \left( \frac{1}{2} \right)

which gives you the angle θ=60\theta = 60^{\circ}. Plugging in k=1k = 1, you get:

θ=cos1(12)+360\theta = \cos^{-1} \left( \frac{1}{2} \right) + 360^{\circ}

which gives you the angle θ=120\theta = 120^{\circ}. Plugging in k=2k = 2, you get:

θ=cos1(12)+720\theta = \cos^{-1} \left( \frac{1}{2} \right) + 720^{\circ}

which gives you the angle θ=180\theta = 180^{\circ}. Plugging in k=3k = 3, you get:

θ=cos1(12)+1080\theta = \cos^{-1} \left( \frac{1}{2} \right) + 1080^{\circ}

which gives you the angle θ=240\theta = 240^{\circ}. Plugging in k=4k = 4, you get:

θ=cos1(12)+1440\theta = \cos^{-1} \left( \frac{1}{2} \right) + 1440^{\circ}

which gives you the angle θ=300\theta = 300^{\circ}. Plugging in k=5k = 5, you get:

θ=cos1(12)+1800\theta = \cos^{-1} \left( \frac{1}{2} \right) + 1800^{\circ}

which gives you the angle θ=0\theta = 0^{\circ}.

Code

Here is some sample code in Python to find the angles in the range 00^{\circ} to 360360^{\circ} that satisfy the equation cos(θ)=12\cos (\theta) = \frac{1}{2}:

import math

def find_angles(): angles = [] for k in range(6): theta = math.acos(0.5) + 2 * math.pi * k angles.append(math.degrees(theta)) return angles

angles = find_angles() print(angles)

Q: What is a trigonometric equation?

A: A trigonometric equation is an equation that involves trigonometric functions, such as sine, cosine, and tangent. These functions relate the angles of a triangle to the ratios of the lengths of its sides.

Q: What is the cosine function?

A: The cosine function is a trigonometric function that is defined as the ratio of the adjacent side to the hypotenuse in a right-angled triangle. It is denoted by the symbol cos(θ)\cos (\theta), where θ\theta is the angle.

Q: How do I solve a trigonometric equation?

A: To solve a trigonometric equation, you need to isolate the trigonometric function and then use the inverse function to find the angle. For example, if you have the equation cos(θ)=12\cos (\theta) = \frac{1}{2}, you can use the inverse cosine function to find the angle θ\theta.

Q: What is the inverse cosine function?

A: The inverse cosine function is a function that takes a value between -1 and 1 and returns the angle whose cosine is that value. It is denoted by the symbol cos1(x)\cos^{-1} (x), where xx is the value.

Q: How do I use the inverse cosine function to solve a trigonometric equation?

A: To use the inverse cosine function to solve a trigonometric equation, you need to isolate the trigonometric function and then take the inverse cosine of both sides of the equation. For example, if you have the equation cos(θ)=12\cos (\theta) = \frac{1}{2}, you can take the inverse cosine of both sides to get:

θ=cos1(12)\theta = \cos^{-1} \left( \frac{1}{2} \right)

Q: What is the reference angle?

A: The reference angle is the acute angle between the terminal side of the angle and the x-axis. It is used to find the angle whose cosine is a given value.

Q: How do I find the reference angle?

A: To find the reference angle, you need to use the inverse cosine function. For example, if you have the equation cos(θ)=12\cos (\theta) = \frac{1}{2}, you can use the inverse cosine function to find the reference angle:

θ=cos1(12)\theta = \cos^{-1} \left( \frac{1}{2} \right)

Q: What is the period of the cosine function?

A: The period of the cosine function is the distance between two consecutive points on the graph of the function that have the same y-coordinate. It is equal to 360360^{\circ}.

Q: How do I find the angles in a given range that satisfy a trigonometric equation?

A: To find the angles in a given range that satisfy a trigonometric equation, you need to use the inverse cosine function and the formula for the period of the cosine function. For example, if you have the equation cos(θ)=12\cos (\theta) = \frac{1}{2} and you want to find the angles in the range 00^{\circ} to 360360^{\circ} that satisfy the equation, you can use the following formula:

θ=cos1(12)+360k\theta = \cos^{-1} \left( \frac{1}{2} \right) + 360^{\circ} k

where kk is an integer.

Q: What is the final answer to the trigonometric equation cos(θ)=12\cos (\theta) = \frac{1}{2}?

A: The final answer to the trigonometric equation cos(θ)=12\cos (\theta) = \frac{1}{2} is 60.0\boxed{60.0}.

Q: How do I use the code to find the angles in a given range that satisfy a trigonometric equation?

A: To use the code to find the angles in a given range that satisfy a trigonometric equation, you need to modify the code to use the inverse cosine function and the formula for the period of the cosine function. For example, if you have the equation cos(θ)=12\cos (\theta) = \frac{1}{2} and you want to find the angles in the range 00^{\circ} to 360360^{\circ} that satisfy the equation, you can use the following code:

import math

def find_angles(): angles = [] for k in range(6): theta = math.acos(0.5) + 2 * math.pi * k angles.append(math.degrees(theta)) return angles

angles = find_angles() print(angles)

This code uses the math.acos function to find the reference angle, and then uses the formula above to find the angles in the range 00^{\circ} to 360360^{\circ}. The math.degrees function is used to convert the angles from radians to degrees. The print statement is used to print the angles.