Determine Trigonometric Ratios

Oct 13, 2025 by wbrum.org 72 views

Introduction

In this article, we will explore the concept of trigonometric ratios in a right-angled triangle. We will use the given triangle $\triangle ABC$ to determine the values of $\sin A$ , $\cos A$ , $\sin C$ , and $\cos C$ . We will also discuss the properties of right-angled triangles and the relationships between the trigonometric ratios.

Properties of Right-Angled Triangles

A right-angled triangle is a triangle with one angle equal to 90 degrees. The side opposite the right angle is called the hypotenuse, and the other two sides are called the legs. In our given triangle $\triangle ABC$ , $AB$ is the hypotenuse, and $BC$ is one of the legs.

Trigonometric Ratios

Trigonometric ratios are used to describe the relationships between the sides and angles of a right-angled triangle. The three basic trigonometric ratios are:

Sine: $\sin A = \frac{\text{opposite}}{\text{hypotenuse}}$
Cosine: $\cos A = \frac{\text{adjacent}}{\text{hypotenuse}}$
Tangent: $\tan A = \frac{\text{opposite}}{\text{adjacent}}$

Determine Trigonometric Ratios

Now, let's use the given triangle $\triangle ABC$ to determine the values of $\sin A$ , $\cos A$ , $\sin C$ , and $\cos C$ .

$\sin A$ and $\cos A$

To determine $\sin A$ and $\cos A$ , we need to find the length of the side opposite angle $A$ and the length of the side adjacent to angle $A$ . Since $AB$ is the hypotenuse, we can use the Pythagorean theorem to find the length of the side opposite angle $A$ .

Pythagorean Theorem

The Pythagorean theorem states that in a right-angled triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides. Mathematically, it can be expressed as:

a^2 + b^2 = c^2

where $a$ and $b$ are the lengths of the two legs, and $c$ is the length of the hypotenuse.

Applying the Pythagorean Theorem

In our given triangle $\triangle ABC$ , we know that $AB = 24 \, \text{cm}$ and $BC = 7 \, \text{cm}$ . We can use the Pythagorean theorem to find the length of the side opposite angle $A$ .

AC^2 = AB^2 - BC^2

AC^2 = 24^2 - 7^2

AC^2 = 576 - 49

AC^2 = 527

AC = \sqrt{527} \, \text{cm}

Now that we have the length of the side opposite angle $A$ , we can determine $\sin A$ .

\sin A = \frac{\text{opposite}}{\text{hypotenuse}} = \frac{AC}{AB} = \frac{\sqrt{527}}{24}

Similarly, we can determine $\cos A$ .

\cos A = \frac{\text{adjacent}}{\text{hypotenuse}} = \frac{BC}{AB} = \frac{7}{24}

$\sin C$ and $\cos C$

To determine $\sin C$ and $\cos C$ , we need to find the length of the side opposite angle $C$ and the length of the side adjacent to angle $C$ . Since $BC$ is the side adjacent to angle $C$ , we can use the Pythagorean theorem to find the length of the side opposite angle $C$ .

Applying the Pythagorean Theorem

In our given triangle $\triangle ABC$ , we know that $AB = 24 \, \text{cm}$ and $BC = 7 \, \text{cm}$ . We can use the Pythagorean theorem to find the length of the side opposite angle $C$ .

AC^2 = AB^2 - BC^2

AC^2 = 24^2 - 7^2

AC^2 = 576 - 49

AC^2 = 527

AC = \sqrt{527} \, \text{cm}

Now that we have the length of the side opposite angle $C$ , we can determine $\sin C$ .

\sin C = \frac{\text{opposite}}{\text{hypotenuse}} = \frac{AC}{AB} = \frac{\sqrt{527}}{24}

Similarly, we can determine $\cos C$ .

\cos C = \frac{\text{adjacent}}{\text{hypotenuse}} = \frac{AB}{AB} = \frac{24}{24} = 1

Conclusion

In this article, we have determined the values of $\sin A$ , $\cos A$ , $\sin C$ , and $\cos C$ in the given triangle $\triangle ABC$ . We have used the Pythagorean theorem to find the length of the sides opposite and adjacent to the angles, and then used the trigonometric ratios to determine the values of the sine and cosine functions.

References

Pythagorean Theorem: A fundamental concept in geometry that describes the relationship between the sides of a right-angled triangle.
Trigonometric Ratios: A set of mathematical functions that describe the relationships between the sides and angles of a right-angled triangle.

Future Work

Q: What is the Pythagorean theorem?

A: The Pythagorean theorem is a fundamental concept in geometry that describes the relationship between the sides of a right-angled triangle. It states that the square of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the other two sides.

Q: How do I use the Pythagorean theorem to find the length of a side?

A: To use the Pythagorean theorem, you need to know the lengths of the other two sides. Let's say you know the length of the hypotenuse (c) and one of the other sides (a). You can use the formula:

c^2 = a^2 + b^2

where b is the length of the other side you want to find.

Q: What are the trigonometric ratios?

A: The trigonometric ratios are a set of mathematical functions that describe the relationships between the sides and angles of a right-angled triangle. The three basic trigonometric ratios are:

Sine: sin(A) = opposite/hypotenuse
Cosine: cos(A) = adjacent/hypotenuse
Tangent: tan(A) = opposite/adjacent

Q: How do I use the trigonometric ratios to find the values of sine, cosine, and tangent?

A: To use the trigonometric ratios, you need to know the lengths of the sides of the triangle and the measure of the angle. Let's say you know the length of the hypotenuse (c) and the length of one of the other sides (a). You can use the formulas:

sin(A) = a/c cos(A) = b/c tan(A) = a/b

where b is the length of the other side.

Q: What is the difference between sine and cosine?

A: Sine and cosine are both trigonometric ratios, but they describe different relationships between the sides and angles of a right-angled triangle. Sine is the ratio of the length of the side opposite the angle to the length of the hypotenuse, while cosine is the ratio of the length of the side adjacent to the angle to the length of the hypotenuse.

Q: How do I use the trigonometric ratios to solve problems?

A: To use the trigonometric ratios to solve problems, you need to identify the given information and the unknown quantity. Then, you can use the formulas to find the values of the trigonometric ratios and solve for the unknown quantity.

Q: What are some common applications of trigonometry?

A: Trigonometry has many common applications in real-life situations, such as:

Navigation: Trigonometry is used in navigation to determine distances and directions.
Physics: Trigonometry is used in physics to describe the motion of objects and the forces acting on them.
Engineering: Trigonometry is used in engineering to design and build structures, such as bridges and buildings.
Computer Science: Trigonometry is used in computer science to create 3D graphics and animations.

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

A: Some common mistakes to avoid when working with trigonometry include:

Not checking units: Make sure to check the units of the given information and the unknown quantity to ensure that they are consistent.
Not using the correct formulas: Make sure to use the correct formulas for the trigonometric ratios and the Pythagorean theorem.
Not simplifying expressions: Make sure to simplify expressions and cancel out common factors to avoid unnecessary calculations.

Conclusion

In this article, we have answered some frequently asked questions about trigonometry, including the Pythagorean theorem, trigonometric ratios, and common applications of trigonometry. We have also discussed some common mistakes to avoid when working with trigonometry. By following these tips and using the formulas and techniques discussed in this article, you can become proficient in trigonometry and apply it to real-life situations.