How to Find Coterminal Angles

Oct 13, 2025 by wbrum.org 100 views

Introduction

In mathematics, angles are a fundamental concept in geometry and trigonometry. Angles are measured in degrees, and they can be positive or negative. A positive angle is measured counterclockwise from the initial side, while a negative angle is measured clockwise from the initial side. Coterminal angles are angles that have the same terminal side, but differ by a full rotation (360 degrees). In this article, we will explore the concept of coterminal angles and determine which of the given angles are coterminal with a 145-degree angle.

What are Coterminal Angles?

Coterminal angles are angles that have the same terminal side, but differ by a full rotation (360 degrees). In other words, if two angles have the same terminal side, but one angle is measured counterclockwise and the other angle is measured clockwise, they are coterminal. For example, 145 degrees and 145 + 360 = 505 degrees are coterminal angles.

How to Find Coterminal Angles

To find coterminal angles, we can add or subtract a full rotation (360 degrees) from the given angle. If we add 360 degrees to the given angle, we get a coterminal angle that is measured counterclockwise. If we subtract 360 degrees from the given angle, we get a coterminal angle that is measured clockwise.

Examples of Coterminal Angles

145 degrees and 145 + 360 = 505 degrees are coterminal angles.
-145 degrees and -145 + 360 = -785 degrees are coterminal angles.
145 degrees and 145 - 360 = -215 degrees are coterminal angles.

Selecting Coterminal Angles with a 145-Degree Angle

Now that we understand what coterminal angles are and how to find them, let's select the angles that are coterminal with a 145-degree angle from the given options.

-575 degrees: This angle is not coterminal with a 145-degree angle because it is not a multiple of 360 degrees away from 145 degrees.
-215 degrees: This angle is coterminal with a 145-degree angle because it is 360 degrees away from 145 degrees.
-145 degrees: This angle is coterminal with a 145-degree angle because it is 0 degrees away from 145 degrees.
-35 degrees: This angle is not coterminal with a 145-degree angle because it is not a multiple of 360 degrees away from 145 degrees.
215 degrees: This angle is coterminal with a 145-degree angle because it is 360 degrees away from 145 degrees.

Conclusion

In conclusion, the angles that are coterminal with a 145-degree angle are -215 degrees, -145 degrees, and 215 degrees. These angles have the same terminal side as the 145-degree angle, but differ by a full rotation (360 degrees). Understanding coterminal angles is essential in mathematics, particularly in geometry and trigonometry. By knowing how to find coterminal angles, we can solve problems involving angles and measure them accurately.

Final Answer

The final answer is:

-575 degrees: No
-215 degrees: Yes
-145 degrees: Yes
-35 degrees: No
215 degrees: Yes
Coterminal Angles Q&A =========================

Frequently Asked Questions about Coterminal Angles

Q: What are coterminal angles?

A: Coterminal angles are angles that have the same terminal side, but differ by a full rotation (360 degrees). In other words, if two angles have the same terminal side, but one angle is measured counterclockwise and the other angle is measured clockwise, they are coterminal.

Q: How do I find coterminal angles?

A: To find coterminal angles, you can add or subtract a full rotation (360 degrees) from the given angle. If you add 360 degrees to the given angle, you get a coterminal angle that is measured counterclockwise. If you subtract 360 degrees from the given angle, you get a coterminal angle that is measured clockwise.

Q: What is the difference between coterminal angles and supplementary angles?

A: Coterminal angles have the same terminal side, but differ by a full rotation (360 degrees). Supplementary angles, on the other hand, add up to 180 degrees. For example, 145 degrees and 505 degrees are coterminal angles, while 145 degrees and 35 degrees are supplementary angles.

Q: Can I have multiple coterminal angles for a given angle?

A: Yes, you can have multiple coterminal angles for a given angle. For example, 145 degrees, 505 degrees, and -215 degrees are all coterminal angles.

Q: How do I determine if two angles are coterminal?

A: To determine if two angles are coterminal, you can check if they have the same terminal side and differ by a full rotation (360 degrees). You can also use the formula: angle1 = angle2 + 360k or angle1 = angle2 - 360k, where k is an integer.

Q: What are some real-world applications of coterminal angles?

A: Coterminal angles have many real-world applications in fields such as engineering, architecture, and navigation. For example, in engineering, coterminal angles are used to design and build structures such as bridges and buildings. In architecture, coterminal angles are used to design and build buildings and other structures. In navigation, coterminal angles are used to determine the direction and location of objects.

Q: Can I use a calculator to find coterminal angles?

A: Yes, you can use a calculator to find coterminal angles. Most calculators have a function to find the coterminal angle of a given angle. You can also use online tools and software to find coterminal angles.

Q: What are some common mistakes to avoid when working with coterminal angles?

A: Some common mistakes to avoid when working with coterminal angles include:

Not checking if the angles have the same terminal side
Not using the correct formula to find coterminal angles
Not considering the direction of the angle (counterclockwise or clockwise)
Not using a calculator or online tool to find coterminal angles

Conclusion

In conclusion, coterminal angles are an essential concept in mathematics, particularly in geometry and trigonometry. By understanding coterminal angles, you can solve problems involving angles and measure them accurately. We hope this Q&A article has helped you understand coterminal angles better and has provided you with the information you need to work with them confidently.

Final Answer

The final answer is:

Q: What are coterminal angles? A: Coterminal angles are angles that have the same terminal side, but differ by a full rotation (360 degrees).
Q: How do I find coterminal angles? A: To find coterminal angles, you can add or subtract a full rotation (360 degrees) from the given angle.
Q: What is the difference between coterminal angles and supplementary angles? A: Coterminal angles have the same terminal side, but differ by a full rotation (360 degrees), while supplementary angles add up to 180 degrees.
Q: Can I have multiple coterminal angles for a given angle? A: Yes, you can have multiple coterminal angles for a given angle.
Q: How do I determine if two angles are coterminal? A: To determine if two angles are coterminal, you can check if they have the same terminal side and differ by a full rotation (360 degrees).
Q: What are some real-world applications of coterminal angles? A: Coterminal angles have many real-world applications in fields such as engineering, architecture, and navigation.
Q: Can I use a calculator to find coterminal angles? A: Yes, you can use a calculator to find coterminal angles.
Q: What are some common mistakes to avoid when working with coterminal angles? A: Some common mistakes to avoid when working with coterminal angles include not checking if the angles have the same terminal side, not using the correct formula to find coterminal angles, not considering the direction of the angle, and not using a calculator or online tool to find coterminal angles.