Podcast
Questions and Answers
What defines an identity in trigonometric equations?
What defines an identity in trigonometric equations?
- An equation that remains true for all values of the variable. (correct)
- A conditional equation that holds true for some values.
- An equation that is only true for certain intervals.
- An equation that has at least one solution.
Which technique is NOT suggested for verifying trigonometric identities?
Which technique is NOT suggested for verifying trigonometric identities?
- Assume both sides are equal and simplify. (correct)
- Factor out the greatest common factor.
- Rewrite the complicated side in terms of sines and cosines.
- Combine fractional expressions using the least common denominator.
If an equation does not satisfy some values in its domain, what is it classified as?
If an equation does not satisfy some values in its domain, what is it classified as?
- An identity.
- A conditional equation. (correct)
- An absolute equation.
- A universal equation.
Which of the following is NOT a fundamental identity type mentioned?
Which of the following is NOT a fundamental identity type mentioned?
When verifying trigonometric identities, which strategy is recommended?
When verifying trigonometric identities, which strategy is recommended?
What is the radian measure of a 90 degree angle?
What is the radian measure of a 90 degree angle?
What is the sine of 180 degrees?
What is the sine of 180 degrees?
What are the coordinates of the point on the unit circle that corresponds to an angle of 3π/4 radians?
What are the coordinates of the point on the unit circle that corresponds to an angle of 3π/4 radians?
What is the tangent of 270 degrees?
What is the tangent of 270 degrees?
Which of the following angles has a cosine value of -1/2?
Which of the following angles has a cosine value of -1/2?
What is the radian measure of 30 degrees?
What is the radian measure of 30 degrees?
Flashcards
Trigonometric Identity
Trigonometric Identity
An equation that is true for all values of the variable within its domain.
Verifying a Trigonometric Identity
Verifying a Trigonometric Identity
Showing that two trigonometric expressions are equal for all valid inputs.
Fundamental Trig Identities
Fundamental Trig Identities
Basic trigonometric relationships between sine, cosine, tangent, etc.
Strategy for verifying Identities
Strategy for verifying Identities
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Conditional Equation
Conditional Equation
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Unit Circle
Unit Circle
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Trigonometric Functions
Trigonometric Functions
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Sine (sin)
Sine (sin)
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Cosine (cos)
Cosine (cos)
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Tangent (tan)
Tangent (tan)
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Key Points (Unit Circle)
Key Points (Unit Circle)
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Radians
Radians
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2π radians
2π radians
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Degrees to Radians
Degrees to Radians
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Radians to Degrees
Radians to Degrees
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Pythagorean Identity
Pythagorean Identity
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Reciprocal Trig Functions
Reciprocal Trig Functions
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Reference Angle
Reference Angle
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Quadrant Signs (sin, cos, tan)
Quadrant Signs (sin, cos, tan)
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Periodic Functions
Periodic Functions
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Trigonometric Period
Trigonometric Period
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Angle and Trig Ratios
Angle and Trig Ratios
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Solving Trig Equations
Solving Trig Equations
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Graphing Trig Functions
Graphing Trig Functions
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Verifying Identities
Verifying Identities
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Unit Circle Coordinates (30° and 45°)
Unit Circle Coordinates (30° and 45°)
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Symmetry Properties (Trig Functions)
Symmetry Properties (Trig Functions)
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Inverse Trig Functions
Inverse Trig Functions
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Arc Length
Arc Length
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Radian Measure (Arc Length/Radius)
Radian Measure (Arc Length/Radius)
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Trigonometric Applications (Real-world)
Trigonometric Applications (Real-world)
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Study Notes
Trigonometric Identities
- Trigonometric identities are equations that are true for all values of the variable in the domain of the equation
- An equation that is not an identity is called a conditional equation. This occurs when some values of the variable in the domain of the equation do not satisfy the equation
Fundamental Trigonometric Identities
-
Reciprocal Identities
- sin x = 1/csc x
- cos x = 1/sec x
- tan x = 1/cot x
- csc x = 1/sin x
- sec x = 1/cos x
- cot x = 1/tan x
-
Quotient Identities
- tan x = sin x/cos x
- cot x = cos x/sin x
-
Pythagorean Identities
- sin² x + cos² x = 1
- 1 + tan² x = sec² x
- 1 + cot² x = csc² x
Even-Odd Identities
- sin(-x) = -sin x
- cos(-x) = cos x
- tan(-x) = -tan x
- csc(-x) = -csc x
- sec(-x) = sec x
- cot(-x) = -cot x
Guidelines for Verifying Trigonometric Identities
- Work with each side of the equation independently. Start with the more complicated side and work towards the other side in a series of steps.
- Analyze the identity and look for opportunities to apply fundamental identities.
- Techniques to utilize include:
- Rewrite the more complicated side in terms of sines and cosines
- Factor out the greatest common factor
- Separate a single-term quotient into two terms
- Combine fractional expressions using the least common denominator
- Multiply the numerator and the denominator by a binomial factor that appears on the other side of the identity
Additional Trigonometric Identities
-
Sum and Difference Identities
- sin(a + b) = sin a cos b + cos a sin b
- sin(a - b) = sin a cos b - cos a sin b
- cos(a + b) = cos a cos b - sin a sin b
- cos(a - b) = cos a cos b + sin a sin b
- tan(a + b) = (tan a + tan b) / (1 - tan a tan b)
- tan(a - b) = (tan a - tan b) / (1 + tan a tan b)
-
Double Angle Identities
- sin 2a = 2 sin a cos a
- cos 2a = cos² a - sin² a = 2 cos² a - 1 = 1 - 2 sin² a
- tan 2a = 2 tan a / (1 - tan² a)
-
Half Angle Identities
- sin (a/2) = ±√((1-cos a)/2)
- cos (a/2) = ±√((1+cos a)/2)
- tan (a/2) = ±√((1 - cos a) / (1 + cos a)) = sin a / (1 + cos a) = (1 - cos a) / sin a
Example Identities to Verify
- csc θ cot θ = sin θ / (1 + cos θ)
- sec x cot x = csc x
- cos² x - cos x sin² x = cos³ x
- (1 + sin x) / cos x = sec x + tan x
Seatwork Examples (Identities to Prove)
- 2 sin² θ = 2 - 2 cos² θ
- csc θ sec θ - cot θ = tan θ
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Description
Test your knowledge of trigonometric identities with this quiz. Explore various reciprocal, quotient, and Pythagorean identities as well as even-odd identities. Understand the key concepts that are crucial for solving trigonometric equations.