21 Cos A 29 20 Suppose A is an acute angle, and sin A 29 Find sin 2A and cos 2A. sin 2A = cos 2A
21 Cos A 29 20 Suppose A is an acute angle, and sin A 29 Find sin 2A and cos 2A. sin 2A = cos 2A
Trigonometry (11th Edition)
11th Edition
ISBN:9780134217437
Author:Margaret L. Lial, John Hornsby, David I. Schneider, Callie Daniels
Publisher:Margaret L. Lial, John Hornsby, David I. Schneider, Callie Daniels
Chapter1: Trigonometric Functions
Section: Chapter Questions
Problem 1RE:
1. Give the measures of the complement and the supplement of an angle measuring 35°.
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![**Example Problem: Find sin(2A) and cos(2A)**
Suppose \( A \) is an acute angle, and
\[ \sin A = \frac{21}{29} \]
\[ \cos A = \frac{20}{29} \]
Find \( \sin 2A \) and \( \cos 2A \).
\[ \sin 2A = \]
\[ \cos 2A = \]
### Solution:
To find \( \sin 2A \) and \( \cos 2A \), we can use the following double-angle identities:
1. \( \sin 2A = 2 \sin A \cos A \)
2. \( \cos 2A = \cos^2 A - \sin^2 A \)
Using the given values:
\[ \sin A = \frac{21}{29} \]
\[ \cos A = \frac{20}{29} \]
First, calculate \( \sin 2A \):
\[ \sin 2A = 2 \sin A \cos A \]
\[ \sin 2A = 2 \left(\frac{21}{29}\right) \left(\frac{20}{29}\right) \]
\[ \sin 2A = 2 \cdot \frac{420}{841} \]
\[ \sin 2A = \frac{840}{841} \]
Now, calculate \( \cos 2A \):
\[ \cos 2A = \cos^2 A - \sin^2 A \]
\[ \cos 2A = \left(\frac{20}{29}\right)^2 - \left(\frac{21}{29}\right)^2 \]
\[ \cos 2A = \frac{400}{841} - \frac{441}{841} \]
\[ \cos 2A = \frac{400 - 441}{841} \]
\[ \cos 2A = \frac{-41}{841} \]
Putting these results in the answer fields:
\[ \sin 2A = \frac{840}{841} \]
\[ \cos 2A = \frac{-41}{841} \]](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fbedff2a8-4b07-409d-bb44-569d0d3dba8b%2F92083615-6570-47ac-8e5c-c9e0df888407%2Fbjvcwdj_processed.png&w=3840&q=75)
Transcribed Image Text:**Example Problem: Find sin(2A) and cos(2A)**
Suppose \( A \) is an acute angle, and
\[ \sin A = \frac{21}{29} \]
\[ \cos A = \frac{20}{29} \]
Find \( \sin 2A \) and \( \cos 2A \).
\[ \sin 2A = \]
\[ \cos 2A = \]
### Solution:
To find \( \sin 2A \) and \( \cos 2A \), we can use the following double-angle identities:
1. \( \sin 2A = 2 \sin A \cos A \)
2. \( \cos 2A = \cos^2 A - \sin^2 A \)
Using the given values:
\[ \sin A = \frac{21}{29} \]
\[ \cos A = \frac{20}{29} \]
First, calculate \( \sin 2A \):
\[ \sin 2A = 2 \sin A \cos A \]
\[ \sin 2A = 2 \left(\frac{21}{29}\right) \left(\frac{20}{29}\right) \]
\[ \sin 2A = 2 \cdot \frac{420}{841} \]
\[ \sin 2A = \frac{840}{841} \]
Now, calculate \( \cos 2A \):
\[ \cos 2A = \cos^2 A - \sin^2 A \]
\[ \cos 2A = \left(\frac{20}{29}\right)^2 - \left(\frac{21}{29}\right)^2 \]
\[ \cos 2A = \frac{400}{841} - \frac{441}{841} \]
\[ \cos 2A = \frac{400 - 441}{841} \]
\[ \cos 2A = \frac{-41}{841} \]
Putting these results in the answer fields:
\[ \sin 2A = \frac{840}{841} \]
\[ \cos 2A = \frac{-41}{841} \]
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