Trigonometry Basics
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Questions and Answers

What is the sine function in relation to a right triangle?

The sine function is defined as the opposite side divided by the hypotenuse.

State the Pythagorean identity and explain its significance.

The Pythagorean identity is sin²(θ) + cos²(θ) = 1, and it establishes a fundamental relationship between the sine and cosine of an angle.

Convert 60 degrees to radians.

60 degrees is equivalent to $ rac{ ext{π}}{3}$ radians.

What are the coordinates of the point corresponding to 45 degrees on the unit circle?

<p>The coordinates for 45 degrees on the unit circle are $ rac{ ext{√2}}{2}$ for both cosine and sine.</p> Signup and view all the answers

Describe the periodicity of the sine and cosine functions.

<p>Both sine and cosine functions are periodic with a period of $2 ext{π}$, meaning their values repeat every $2 ext{π}$ radians.</p> Signup and view all the answers

How can the Law of Sines be applied to find an unknown angle in a triangle?

<p>The Law of Sines states that $ rac{a}{ ext{sin}(A)} = rac{b}{ ext{sin}(B)}$, allowing us to find an unknown angle if the sides and one angle are known.</p> Signup and view all the answers

What is the tangent of 30 degrees, and why is it significant?

<p>The tangent of 30 degrees is $ rac{ ext{√3}}{3}$, which illustrates the ratio of the opposite side to the adjacent side in a right triangle.</p> Signup and view all the answers

Explain the significance of the unit circle in trigonometry.

<p>The unit circle provides a visual representation of the sine and cosine functions, with points on the circle corresponding to angles and their trigonometric values.</p> Signup and view all the answers

What does the Law of Cosines describe and when is it used?

<p>The Law of Cosines, stated as $c^2 = a^2 + b^2 - 2ab ext{cos}(C)$, helps find unknown sides or angles in any triangle.</p> Signup and view all the answers

Identify the range of the tangent function and its periodicity.

<p>The tangent function has a range of all real numbers and is periodic with a period of $ ext{π}$.</p> Signup and view all the answers

Study Notes

Trigonometry

  • Definition: Branch of mathematics dealing with the relationships between the angles and sides of triangles, particularly right triangles.

  • Basic Functions:

    • Sine (sin): Opposite side / Hypotenuse
    • Cosine (cos): Adjacent side / Hypotenuse
    • Tangent (tan): Opposite side / Adjacent side
    • Reciprocal Functions:
      • Cosecant (csc): 1/sin
      • Secant (sec): 1/cos
      • Cotangent (cot): 1/tan
  • Pythagorean Identity:

    • sin²(θ) + cos²(θ) = 1
  • Angle Measures:

    • Degrees: Full circle = 360°
    • Radians: Full circle = 2π radians
    • Conversion: degrees to radians: θ radians = (π/180) * θ degrees
  • Unit Circle:

    • A circle with a radius of 1 centered at the origin.
    • Coordinates of points on the circle represent (cos(θ), sin(θ)).
    • Important angles:
      • 0°, 30°, 45°, 60°, 90° (and their corresponding coordinates)
  • Trigonometric Values:

    • Common angles:
      • sin(30°) = 1/2, cos(30°) = √3/2, tan(30°) = √3/3
      • sin(45°) = √2/2, cos(45°) = √2/2, tan(45°) = 1
      • sin(60°) = √3/2, cos(60°) = 1/2, tan(60°) = √3
  • Trigonometric Equations:

    • Can involve finding the angle θ given values of trigonometric functions (e.g., sin(θ) = 0.5).
    • Principal solutions often found in the first and second quadrants for sine, first and fourth for cosine, and all quadrants for tangent.
  • Applications:

    • Used in physics (wave motion, mechanics), engineering (angles of elevation), architecture, computer graphics, and more.
  • Graphs of Trigonometric Functions:

    • Sin and Cos: Periodic with a period of 2π. Range: [-1, 1].
    • Tan: Periodic with a period of π. Range: All real numbers.
  • Law of Sines:

    • a/sin(A) = b/sin(B) = c/sin(C)
    • For any triangle (not just right triangles).
  • Law of Cosines:

    • c² = a² + b² - 2ab*cos(C)
    • Useful for finding angles or sides in any triangle.

Trigonometry Basics

  • Trigonometry is focused on the relationships between the angles and sides of triangles, especially right triangles.
  • Basic trigonometric functions include:
    • Sine (sin): Opposite side divided by Hypotenuse
    • Cosine (cos): Adjacent side divided by Hypotenuse
    • Tangent (tan): Opposite side divided by Adjacent side
  • The reciprocal functions of sine, cosine, and tangent are cosecant (csc), secant (sec), and cotangent (cot), respectively.

Key Identities and Properties

  • The Pythagorean Identity states: sin²(θ) + cos²(θ) = 1
  • Angles can be measured in degrees (full circle = 360°) or radians (full circle = 2π radians).
  • To convert degrees to radians: θ radians = (π/180) * θ degrees.

The Unit Circle

  • The unit circle is a circle with a radius of 1 centered at the origin.
  • Coordinates of points on the unit circle represent (cos(θ), sin(θ)).
  • Important angles on the unit circle include: 0°, 30°, 45°, 60°, 90° (and their corresponding coordinates).

Trigonometric Values and Applications

  • For common angles:
    • sin(30°) = 1/2, cos(30°) = √3/2, tan(30°) = √3/3
    • sin(45°) = √2/2, cos(45°) = √2/2, tan(45°) = 1
    • sin(60°) = √3/2, cos(60°) = 1/2, tan(60°) = √3
  • Trigonometry is used in physics (wave motion, mechanics), engineering (angles of elevation), architecture, computer graphics, and more.

Graphs and Laws

  • The graphs of sine and cosine functions are periodic with a period of 2π and have a range of [-1, 1].
  • The graph of the tangent function is periodic with a period of π and has a range of all real numbers.
  • The Law of Sines states: a/sin(A) = b/sin(B) = c/sin(C), which applies to any triangle.
  • The Law of Cosines states: c² = a² + b² - 2ab*cos(C) and is useful for finding angles or sides in any triangle.

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Explore the foundations of trigonometry, including definitions, basic functions, and important identities. This quiz covers sine, cosine, tangent, and their reciprocal functions, along with angle measures and the unit circle. Perfect for students looking to solidify their understanding of trigonometric concepts.

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