Podcast
Questions and Answers
What is the formula for cos(A + B)?
What is the formula for cos(A + B)?
- sin A cos B + cos A sin B
- sin A sin B - cos A cos B
- cos A cos B + sin A sin B
- cos A cos B - sin A sin B (correct)
The formula sin(π/2-A) = cos A is always true.
The formula sin(π/2-A) = cos A is always true.
True (A)
What is the formula for tan(A+B)?
What is the formula for tan(A+B)?
[(tan A + tan B)/(1 – tan A tan B)]
The formula for sin(A -B) is _______.
The formula for sin(A -B) is _______.
Match the following trigonometric identities with their formulas:
Match the following trigonometric identities with their formulas:
What is the formula for cos3A?
What is the formula for cos3A?
What is the value of sin(π-A) in terms of sin A?
What is the value of sin(π-A) in terms of sin A?
The formula tan(A+B) = [(tan A + tan B)/(1 + tan A tan B)] is always true.
The formula tan(A+B) = [(tan A + tan B)/(1 + tan A tan B)] is always true.
What is the formula for cos2A in terms of sin A and cos A?
What is the formula for cos2A in terms of sin A and cos A?
The formula sin(A+B) sin(A–B) = _______
The formula sin(A+B) sin(A–B) = _______
What is the value of tan 2A in terms of tan A?
What is the value of tan 2A in terms of tan A?
Match the following trigonometric identities with their formulas:
Match the following trigonometric identities with their formulas:
The formula sin(A+B) = sin A cos B + cos A sin B is always true.
The formula sin(A+B) = sin A cos B + cos A sin B is always true.
Study Notes
Trigonometric Identities: Sum and Difference Formulas
cos(A + B) = cos A cos B – sin A sin B
cos(A – B) = cos A cos B + sin A sin B
sin(A+B) = sin A cos B + cos A sin B
sin(A -B) = sin A cos B – cos A sin B
Complementary Angle Identities
sin(π/2-A) = cos A
cos(π/2-A) = sin A
sin(π-A) = sin A
cos(π-A) = -cos A
sin(π+A)=-sin A
cos(π+A)=-cos A
sin(2π-A) = -sin A
cos(2π-A) = cos A
Tangent and Cotangent Identities
tan(A+B) = [(tan A + tan B)/(1 – tan A tan B)]
(if none of the angles A, B, and (A ± B) is an odd multiple of π/2)tan(A-B) = [(tan A – tan B)/(1 + tan A tan B)]
(if none of the angles A, B, and (A ± B) is an odd multiple of π/2)cot(A+B) = [(cot A cot B − 1)/(cot B + cot A)]
(if none of the angles A, B, and (A ± B) is a multiple of π)cot(A-B) = [(cot A cot B + 1)/(cot B – cot A)]
(if none of the angles A, B, and (A ± B) is a multiple of π)
Product Identities
cos(A+B) cos(A–B)=cos2A–sin2B=cos2B–sin2A
sin(A+B) sin(A–B) = sin2A–sin2B=cos2B–cos2A
Sum-to-Product Identities
sinA+sinB = 2 sin (A+B)/2 cos (A-B)/2
Double Angle Identities
sin2A = 2sinA cosA = [2tan A /(1+tan2A)]
cos2A = cos2A–sin2A = 1–2sin2A = 2cos2A–1= [(1-tan2A)/(1+tan2A)]
tan 2A = (2 tan A)/(1-tan2A)
Triple Angle Identities
sin3A = 3sinA – 4sin3A
cos3A = 4cos3A – 3cosA
tan3A = [3tanA–tan3A]/[1−3tan2A]
Trigonometric Identities: Sum and Difference Formulas
cos(A + B) = cos A cos B – sin A sin B
cos(A – B) = cos A cos B + sin A sin B
sin(A+B) = sin A cos B + cos A sin B
sin(A -B) = sin A cos B – cos A sin B
Complementary Angle Identities
sin(π/2-A) = cos A
cos(π/2-A) = sin A
sin(π-A) = sin A
cos(π-A) = -cos A
sin(π+A)=-sin A
cos(π+A)=-cos A
sin(2π-A) = -sin A
cos(2π-A) = cos A
Tangent and Cotangent Identities
tan(A+B) = [(tan A + tan B)/(1 – tan A tan B)]
(if none of the angles A, B, and (A ± B) is an odd multiple of π/2)tan(A-B) = [(tan A – tan B)/(1 + tan A tan B)]
(if none of the angles A, B, and (A ± B) is an odd multiple of π/2)cot(A+B) = [(cot A cot B − 1)/(cot B + cot A)]
(if none of the angles A, B, and (A ± B) is a multiple of π)cot(A-B) = [(cot A cot B + 1)/(cot B – cot A)]
(if none of the angles A, B, and (A ± B) is a multiple of π)
Product Identities
cos(A+B) cos(A–B)=cos2A–sin2B=cos2B–sin2A
sin(A+B) sin(A–B) = sin2A–sin2B=cos2B–cos2A
Sum-to-Product Identities
sinA+sinB = 2 sin (A+B)/2 cos (A-B)/2
Double Angle Identities
sin2A = 2sinA cosA = [2tan A /(1+tan2A)]
cos2A = cos2A–sin2A = 1–2sin2A = 2cos2A–1= [(1-tan2A)/(1+tan2A)]
tan 2A = (2 tan A)/(1-tan2A)
Triple Angle Identities
sin3A = 3sinA – 4sin3A
cos3A = 4cos3A – 3cosA
tan3A = [3tanA–tan3A]/[1−3tan2A]
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Description
Formulas for trigonometric functions such as sin, cos, and tan with angle additions and subtractions. Includes identities for special angles like π/2 and π.