The Trigonometric Identity

Oct 13, 2025 by wbrum.org 84 views

Introduction

Trigonometry is a branch of mathematics that deals with the relationships between the sides and angles of triangles. In a right triangle, the trigonometric functions such as sine, cosine, and tangent are used to describe the relationships between the angles and the sides of the triangle. In this article, we will explore the trigonometric identity $\tan X = \frac{\sin X}{\cos X}$ and use it to determine the equation relating the acute angles, $A$ and $C$ , of a right triangle $ABC$ .

The Trigonometric Identity

The trigonometric identity $\tan X = \frac{\sin X}{\cos X}$ is a fundamental concept in trigonometry. It states that the tangent of an angle $X$ is equal to the ratio of the sine of the angle to the cosine of the angle. This identity can be used to relate the angles and sides of a right triangle.

Right Triangle $ABC$

In a right triangle $ABC$ , the angle $A$ is the acute angle opposite the side $a$ , the angle $B$ is the right angle, and the angle $C$ is the acute angle opposite the side $c$ . The side $a$ is the side opposite the angle $A$ , the side $b$ is the side opposite the angle $B$ , and the side $c$ is the side opposite the angle $C$ .

Using the Trigonometric Identity

Using the trigonometric identity $\tan X = \frac{\sin X}{\cos X}$ , we can relate the angles and sides of the right triangle $ABC$ . We can start by using the identity to express the tangent of the angle $A$ in terms of the sine and cosine of the angle $A$ .

\tan A = \frac{\sin A}{\cos A}

We can also use the identity to express the tangent of the angle $C$ in terms of the sine and cosine of the angle $C$ .

\tan C = \frac{\sin C}{\cos C}

Relating the Angles and Sides

Now that we have expressed the tangents of the angles $A$ and $C$ in terms of the sines and cosines of the angles, we can relate the angles and sides of the right triangle $ABC$ . We can start by using the fact that the tangent of an angle is equal to the ratio of the opposite side to the adjacent side.

\tan A = \frac{a}{b}

\tan C = \frac{c}{b}

We can also use the fact that the sine of an angle is equal to the ratio of the opposite side to the hypotenuse.

\sin A = \frac{a}{c}

\sin C = \frac{c}{c} = 1

We can also use the fact that the cosine of an angle is equal to the ratio of the adjacent side to the hypotenuse.

\cos A = \frac{b}{c}

\cos C = \frac{b}{c}

Determining the Equation

Now that we have related the angles and sides of the right triangle $ABC$ , we can determine the equation that is true. We can start by using the fact that the tangent of an angle is equal to the ratio of the opposite side to the adjacent side.

\tan A = \frac{a}{b}

\tan C = \frac{c}{b}

We can also use the fact that the sine of an angle is equal to the ratio of the opposite side to the hypotenuse.

\sin A = \frac{a}{c}

\sin C = \frac{c}{c} = 1

We can also use the fact that the cosine of an angle is equal to the ratio of the adjacent side to the hypotenuse.

\cos A = \frac{b}{c}

\cos C = \frac{b}{c}

Using these relationships, we can determine the equation that is true.

\tan A = \frac{\sin A}{\cos A}

\tan C = \frac{\sin C}{\cos C}

\tan A = \frac{\sin A}{\sin C}

Conclusion

In this article, we have used the trigonometric identity $\tan X = \frac{\sin X}{\cos X}$ to determine the equation that is true relating the acute angles, $A$ and $C$ , of a right triangle $ABC$ . We have shown that the equation $\tan A = \frac{\sin A}{\sin C}$ is true.

References

[1] "Trigonometry" by Michael Corral
[2] "Right Triangle Trigonometry" by Paul Dawkins

Final Answer

$The final answer is: $\boxed{\tan A = \frac{\sin A}{\sin C}}$<br/> **Trigonometry Q&A: Understanding Right Triangles**$

Introduction

Trigonometry is a branch of mathematics that deals with the relationships between the sides and angles of triangles. In a right triangle, the trigonometric functions such as sine, cosine, and tangent are used to describe the relationships between the angles and the sides of the triangle. In this article, we will answer some frequently asked questions about trigonometry and right triangles.

Q: What is the trigonometric identity $\tan X = \frac{\sin X}{\cos X}$ ?

A: The trigonometric identity $\tan X = \frac{\sin X}{\cos X}$ is a fundamental concept in trigonometry. It states that the tangent of an angle $X$ is equal to the ratio of the sine of the angle to the cosine of the angle.

Q: How do I use the trigonometric identity to relate the angles and sides of a right triangle?

A: To use the trigonometric identity to relate the angles and sides of a right triangle, you can start by expressing the tangent of an angle in terms of the sine and cosine of the angle. For example, if you want to relate the angles and sides of a right triangle $ABC$ , you can use the identity to express the tangent of the angle $A$ in terms of the sine and cosine of the angle $A$ .

Q: What is the relationship between the tangent of an angle and the sides of a right triangle?

A: The tangent of an angle is equal to the ratio of the opposite side to the adjacent side. For example, if you want to find the tangent of the angle $A$ in a right triangle $ABC$ , you can use the fact that the tangent of the angle $A$ is equal to the ratio of the side $a$ to the side $b$ .

Q: How do I use the sine and cosine functions to relate the angles and sides of a right triangle?

A: To use the sine and cosine functions to relate the angles and sides of a right triangle, you can start by using the fact that the sine of an angle is equal to the ratio of the opposite side to the hypotenuse. For example, if you want to relate the angles and sides of a right triangle $ABC$ , you can use the fact that the sine of the angle $A$ is equal to the ratio of the side $a$ to the hypotenuse $c$ .

Q: What is the relationship between the cosine of an angle and the sides of a right triangle?

A: The cosine of an angle is equal to the ratio of the adjacent side to the hypotenuse. For example, if you want to find the cosine of the angle $A$ in a right triangle $ABC$ , you can use the fact that the cosine of the angle $A$ is equal to the ratio of the side $b$ to the hypotenuse $c$ .

Q: How do I use the trigonometric identity to determine the equation that is true relating the acute angles, $A$ and $C$ , of a right triangle $ABC$ ?

A: To use the trigonometric identity to determine the equation that is true relating the acute angles, $A$ and $C$ , of a right triangle $ABC$ , you can start by expressing the tangent of the angle $A$ in terms of the sine and cosine of the angle $A$ . You can then use the fact that the tangent of an angle is equal to the ratio of the opposite side to the adjacent side to relate the angles and sides of the triangle.

Q: What is the final answer to the problem of determining the equation that is true relating the acute angles, $A$ and $C$ , of a right triangle $ABC$ ?

A: The final answer to the problem of determining the equation that is true relating the acute angles, $A$ and $C$ , of a right triangle $ABC$ is $\boxed{\tan A = \frac{\sin A}{\sin C}}$ .

Conclusion

In this article, we have answered some frequently asked questions about trigonometry and right triangles. We have shown how to use the trigonometric identity $\tan X = \frac{\sin X}{\cos X}$ to relate the angles and sides of a right triangle, and how to use the sine and cosine functions to relate the angles and sides of a right triangle. We have also shown how to use the trigonometric identity to determine the equation that is true relating the acute angles, $A$ and $C$ , of a right triangle $ABC$ .

References

[1] "Trigonometry" by Michael Corral
[2] "Right Triangle Trigonometry" by Paul Dawkins

Final Answer

The final answer is: $\boxed{\tan A = \frac{\sin A}{\sin C}}$