Questions and Answers
What is the relationship defined by the sine function in a right triangle?
The sine function is defined as the ratio of the opposite side to the hypotenuse.
Explain the significance of the Pythagorean identity in trigonometry.
The Pythagorean identity states that sin²(θ) + cos²(θ) = 1, which is fundamental for expressing trigonometric functions in terms of each other.
What are the coordinates of the key angle π/4 on the unit circle?
The coordinates of the angle π/4 on the unit circle are (√2/2, √2/2).
Describe how the tangent function is defined in terms of sine and cosine.
Signup and view all the answers
What is the purpose of the Law of Sines in trigonometry?
Signup and view all the answers
Identify the primary difference between the sine wave and the cosine wave.
Signup and view all the answers
What does the reciprocal function cosecant represent?
Signup and view all the answers
How are angle sum identities useful in solving trigonometric problems?
Signup and view all the answers
What is the periodicity of the tangent function?
Signup and view all the answers
What are inverse trigonometric functions and why are they significant?
Signup and view all the answers
Study Notes
Trigonometry
-
Definition: Study of 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 = Hypotenuse / Opposite side
- Secant (sec): 1/cos = Hypotenuse / Adjacent side
- Cotangent (cot): 1/tan = Adjacent side / Opposite side
-
Trigonometric Identities:
- Pythagorean Identity: sin²(θ) + cos²(θ) = 1
-
Angle Sum/Difference Identities:
- sin(α ± β) = sin(α)cos(β) ± cos(α)sin(β)
- cos(α ± β) = cos(α)cos(β) ∓ sin(α)sin(β)
- tan(α ± β) = (tan(α) ± tan(β)) / (1 ∓ tan(α)tan(β))
-
Unit Circle:
- A circle with a radius of 1 centered at the origin (0,0).
- Angles measured in radians; key angles: 0, π/6, π/4, π/3, π/2, π, etc.
- Coordinates correspond to (cos(θ), sin(θ)).
-
Applications:
- Used in various fields such as physics, engineering, architecture, and astronomy.
- Analyzing periodic phenomena like sound waves and light waves.
-
Graphing Trigonometric Functions:
- Sine Wave: Starts at (0,0), periodic with a range from -1 to 1.
- Cosine Wave: Starts at (0,1), also periodic with a range from -1 to 1.
- Tangent Wave: Periodic with vertical asymptotes; range is all real numbers.
-
Inverse Functions:
- Arcsine (sin⁻¹): Function that gives the angle whose sine is a given number.
- Arccosine (cos⁻¹): Function that gives the angle whose cosine is a given number.
- Arctangent (tan⁻¹): Function that gives the angle whose tangent is a given number.
-
Law of Sines:
- In any triangle: (a/sin(A)) = (b/sin(B)) = (c/sin(C))
- Used to find unknown sides or angles in non-right triangles.
-
Law of Cosines:
- For any triangle: c² = a² + b² - 2ab*cos(C)
- Useful for calculating a side or angle when two sides and the included angle are known.
-
Common Trigonometric Values (at key angles):
- sin(0) = 0, sin(30) = 1/2, sin(45) = √2/2, sin(60) = √3/2, sin(90) = 1
- cos(0) = 1, cos(30) = √3/2, cos(45) = √2/2, cos(60) = 1/2, cos(90) = 0
- tan(0) = 0, tan(30) = √3/3, tan(45) = 1, tan(60) = √3, tan(90) = undefined
These notes cover the essential concepts and relationships in trigonometry, providing a solid foundation for further study.
Trigonometry Overview
- Study of relationships between angles and sides of triangles, especially right triangles.
Basic Functions
- Sine (sin): Ratio of opposite side to hypotenuse.
- Cosine (cos): Ratio of adjacent side to hypotenuse.
- Tangent (tan): Ratio of opposite side to adjacent side.
Reciprocal Functions
- Cosecant (csc): Hypotenuse divided by opposite side (1/sin).
- Secant (sec): Hypotenuse divided by adjacent side (1/cos).
- Cotangent (cot): Adjacent side divided by opposite side (1/tan).
Trigonometric Identities
- Pythagorean Identity: sin²(θ) + cos²(θ) = 1, foundational for relations in trigonometry.
-
Angle Sum/Difference Identities:
- sin(α ± β) = sin(α)cos(β) ± cos(α)sin(β)
- cos(α ± β) = cos(α)cos(β) ∓ sin(α)sin(β)
- tan(α ± β) = (tan(α) ± tan(β)) / (1 ∓ tan(α)tan(β))
Unit Circle
- Circle with radius 1, centered at (0,0); angles measured in radians.
- Key angles include 0, π/6, π/4, π/3, π/2, π, with coordinates corresponding to (cos(θ), sin(θ)).
Applications of Trigonometry
- Utilized in physics, engineering, architecture, and astronomy for analyzing periodic phenomena including sound and light waves.
Graphing Trigonometric Functions
- Sine Wave: Begins at (0,0), periodic with a range from -1 to 1.
- Cosine Wave: Begins at (0,1), periodic with a range from -1 to 1.
- Tangent Wave: Periodic with vertical asymptotes; has a range of all real numbers.
Inverse Functions
- Arcsine (sin⁻¹): Returns angle whose sine equals a given value.
- Arccosine (cos⁻¹): Returns angle whose cosine equals a given value.
- Arctangent (tan⁻¹): Returns angle whose tangent equals a given value.
Law of Sines
- For any triangle: (a/sin(A)) = (b/sin(B)) = (c/sin(C), useful for finding unknown sides or angles in non-right triangles.
Law of Cosines
- For any triangle: c² = a² + b² - 2ab*cos(C), helps calculate a side or angle when two sides and the included angle are known.
Common Trigonometric Values at Key Angles
- Sine Values: sin(0) = 0, sin(30) = 1/2, sin(45) = √2/2, sin(60) = √3/2, sin(90) = 1.
- Cosine Values: cos(0) = 1, cos(30) = √3/2, cos(45) = √2/2, cos(60) = 1/2, cos(90) = 0.
- Tangent Values: tan(0) = 0, tan(30) = √3/3, tan(45) = 1, tan(60) = √3, tan(90) = undefined.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Explore the fundamental concepts of trigonometry including the relationships between angles and sides of triangles. This quiz covers basic and reciprocal functions such as sine, cosine, and tangent. Perfect for students looking to solidify their understanding of trigonometric principles.
