Given the Pythagorean theorem a² + b² = c² where a and b are the lengths of the perpendicular sides of a right triangle and c is the length of the hypotenuse. Derive the trigonometric identity sin² (0) + cos² (0) = 1.

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...
icon
Related questions
Question
Given the Pythagorean theorem

\[ a^2 + b^2 = c^2 \]

where \( a \) and \( b \) are the lengths of the perpendicular sides of a right triangle and \( c \) is the length of the hypotenuse. Derive the trigonometric identity

\[ \sin^2(\theta) + \cos^2(\theta) = 1. \]

Explanation:

1. **Pythagorean Theorem**: The theorem states that in a right triangle, the square of the length of the hypotenuse \( c \) is equal to the sum of the squares of the lengths of the other two sides \( a \) and \( b \).

2. **Right Triangle Definitions**:
   - Sine of angle \( \theta \): \(\sin(\theta) = \frac{\text{Opposite}}{\text{Hypotenuse}}\)
   - Cosine of angle \( \theta \): \(\cos(\theta) = \frac{\text{Adjacent}}{\text{Hypotenuse}}\)

3. **Expressing in terms of a, b, and c**:
   - Let us assume that in the given right triangle, side \( a \) is opposite to angle \( \theta \), side \( b \) is adjacent to angle \( \theta \), and \( c \) is the hypotenuse.
   - Then \(\sin(\theta) = \frac{a}{c}\) and \(\cos(\theta) = \frac{b}{c}\).

4. **Square both sides**:
   - \(\sin^2(\theta) = \left(\frac{a}{c}\right)^2 = \frac{a^2}{c^2}\)
   - \(\cos^2(\theta) = \left(\frac{b}{c}\right)^2 = \frac{b^2}{c^2}\)

5. **Add the squared terms**:
   - \(\sin^2(\theta) + \cos^2(\theta) = \frac{a^2}{c^2} + \frac{b^2}{c^2} = \frac{a^2 + b^2}{c^2}\)

6. **Apply the Pythagorean theorem**:
   - According to the Pythagorean theorem, \( a^2 +
Transcribed Image Text:Given the Pythagorean theorem \[ a^2 + b^2 = c^2 \] where \( a \) and \( b \) are the lengths of the perpendicular sides of a right triangle and \( c \) is the length of the hypotenuse. Derive the trigonometric identity \[ \sin^2(\theta) + \cos^2(\theta) = 1. \] Explanation: 1. **Pythagorean Theorem**: The theorem states that in a right triangle, the square of the length of the hypotenuse \( c \) is equal to the sum of the squares of the lengths of the other two sides \( a \) and \( b \). 2. **Right Triangle Definitions**: - Sine of angle \( \theta \): \(\sin(\theta) = \frac{\text{Opposite}}{\text{Hypotenuse}}\) - Cosine of angle \( \theta \): \(\cos(\theta) = \frac{\text{Adjacent}}{\text{Hypotenuse}}\) 3. **Expressing in terms of a, b, and c**: - Let us assume that in the given right triangle, side \( a \) is opposite to angle \( \theta \), side \( b \) is adjacent to angle \( \theta \), and \( c \) is the hypotenuse. - Then \(\sin(\theta) = \frac{a}{c}\) and \(\cos(\theta) = \frac{b}{c}\). 4. **Square both sides**: - \(\sin^2(\theta) = \left(\frac{a}{c}\right)^2 = \frac{a^2}{c^2}\) - \(\cos^2(\theta) = \left(\frac{b}{c}\right)^2 = \frac{b^2}{c^2}\) 5. **Add the squared terms**: - \(\sin^2(\theta) + \cos^2(\theta) = \frac{a^2}{c^2} + \frac{b^2}{c^2} = \frac{a^2 + b^2}{c^2}\) 6. **Apply the Pythagorean theorem**: - According to the Pythagorean theorem, \( a^2 +
Expert Solution
steps

Step by step

Solved in 3 steps with 3 images

Blurred answer
Recommended textbooks for you
Calculus: Early Transcendentals
Calculus: Early Transcendentals
Calculus
ISBN:
9781285741550
Author:
James Stewart
Publisher:
Cengage Learning
Thomas' Calculus (14th Edition)
Thomas' Calculus (14th Edition)
Calculus
ISBN:
9780134438986
Author:
Joel R. Hass, Christopher E. Heil, Maurice D. Weir
Publisher:
PEARSON
Calculus: Early Transcendentals (3rd Edition)
Calculus: Early Transcendentals (3rd Edition)
Calculus
ISBN:
9780134763644
Author:
William L. Briggs, Lyle Cochran, Bernard Gillett, Eric Schulz
Publisher:
PEARSON
Calculus: Early Transcendentals
Calculus: Early Transcendentals
Calculus
ISBN:
9781319050740
Author:
Jon Rogawski, Colin Adams, Robert Franzosa
Publisher:
W. H. Freeman
Precalculus
Precalculus
Calculus
ISBN:
9780135189405
Author:
Michael Sullivan
Publisher:
PEARSON
Calculus: Early Transcendental Functions
Calculus: Early Transcendental Functions
Calculus
ISBN:
9781337552516
Author:
Ron Larson, Bruce H. Edwards
Publisher:
Cengage Learning