Use the sum-to-product identities to rewrite the expression. sin 18° + sin 10° Which expression is equal to sin 18° + sin 10°? O A. -2 sin 14° sin 4° O B. 2 cos 14° sin 4° O C. 2 sin 14° cos 4° D. 2 cos 14° cos 4°
Use the sum-to-product identities to rewrite the expression. sin 18° + sin 10° Which expression is equal to sin 18° + sin 10°? O A. -2 sin 14° sin 4° O B. 2 cos 14° sin 4° O C. 2 sin 14° cos 4° D. 2 cos 14° cos 4°
Calculus: Early Transcendentals
8th Edition
ISBN:9781285741550
Author:James Stewart
Publisher:James Stewart
Chapter1: Functions And Models
Section: Chapter Questions
Problem 1RCC: (a) What is a function? What are its domain and range? (b) What is the graph of a function? (c) How...
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![### Using Sum-to-Product Identities
Use the sum-to-product identities to rewrite the expression:
\[ \sin 18^\circ + \sin 10^\circ \]
### Question
Which expression is equal to \( \sin 18^\circ + \sin 10^\circ \)?
- A. \(-2 \sin 14^\circ \sin 4^\circ\)
- B. \(2 \cos 14^\circ \sin 4^\circ\)
- C. \(2 \sin 14^\circ \cos 4^\circ\)
- D. \(2 \cos 14^\circ \cos 4^\circ\)
Click to select your answer.
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### Explanation
This question asks you to use the sum-to-product identities to simplify the given trigonometric expression.
Sum-to-product identities are trigonometric identities that express sums of sines or cosines as products of sines and cosines. The relevant identities are:
\[ \sin a + \sin b = 2 \sin \left(\frac{a+b}{2}\right) \cos \left(\frac{a-b}{2}\right) \]
Here, if we let \( a = 18^\circ \) and \( b = 10^\circ \), the expression \( \sin 18^\circ + \sin 10^\circ \) can be rewritten as follows:
\[ \sin 18^\circ + \sin 10^\circ = 2 \sin \left(\frac{18^\circ + 10^\circ}{2}\right) \cos \left(\frac{18^\circ - 10^\circ}{2}\right) \]
\[ = 2 \sin \left(\frac{28^\circ}{2}\right) \cos \left(\frac{8^\circ}{2}\right) \]
\[ = 2 \sin 14^\circ \cos 4^\circ \]
Therefore, the correct answer is option C:
### Correct Answer: C. \(2 \sin 14^\circ \cos 4^\circ\)](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F88043793-ea9c-47cb-8de9-bc98093828be%2Ff015c2bb-1526-45da-9fdd-5673a9766a54%2Fhdf09y9_processed.jpeg&w=3840&q=75)
Transcribed Image Text:### Using Sum-to-Product Identities
Use the sum-to-product identities to rewrite the expression:
\[ \sin 18^\circ + \sin 10^\circ \]
### Question
Which expression is equal to \( \sin 18^\circ + \sin 10^\circ \)?
- A. \(-2 \sin 14^\circ \sin 4^\circ\)
- B. \(2 \cos 14^\circ \sin 4^\circ\)
- C. \(2 \sin 14^\circ \cos 4^\circ\)
- D. \(2 \cos 14^\circ \cos 4^\circ\)
Click to select your answer.
[Button: Save for Later]
### Explanation
This question asks you to use the sum-to-product identities to simplify the given trigonometric expression.
Sum-to-product identities are trigonometric identities that express sums of sines or cosines as products of sines and cosines. The relevant identities are:
\[ \sin a + \sin b = 2 \sin \left(\frac{a+b}{2}\right) \cos \left(\frac{a-b}{2}\right) \]
Here, if we let \( a = 18^\circ \) and \( b = 10^\circ \), the expression \( \sin 18^\circ + \sin 10^\circ \) can be rewritten as follows:
\[ \sin 18^\circ + \sin 10^\circ = 2 \sin \left(\frac{18^\circ + 10^\circ}{2}\right) \cos \left(\frac{18^\circ - 10^\circ}{2}\right) \]
\[ = 2 \sin \left(\frac{28^\circ}{2}\right) \cos \left(\frac{8^\circ}{2}\right) \]
\[ = 2 \sin 14^\circ \cos 4^\circ \]
Therefore, the correct answer is option C:
### Correct Answer: C. \(2 \sin 14^\circ \cos 4^\circ\)
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