Skip to main content
Ch. 3 - Trigonometric Identities and Equations
Blitzer - Trigonometry 3rd Edition
Blitzer3rd EditionTrigonometryISBN: 9780137316601Non è quello che usi tu?Cambia libro di testo
Capitolo 3, Problema 22

In Exercises 1–60, verify each identity. cot² t /csc t = csc t - sin t

Guida verificata passo dopo passo
1
Start with the left-hand side (LHS) of the identity: \( \frac{\cot^{2} t}{\csc t} \). Recall the definitions of cotangent and cosecant in terms of sine and cosine: \( \cot t = \frac{\cos t}{\sin t} \) and \( \csc t = \frac{1}{\sin t} \).
Rewrite \( \cot^{2} t \) as \( \left( \frac{\cos t}{\sin t} \right)^{2} = \frac{\cos^{2} t}{\sin^{2} t} \). Substitute this and \( \csc t = \frac{1}{\sin t} \) into the LHS to get \( \frac{\frac{\cos^{2} t}{\sin^{2} t}}{\frac{1}{\sin t}} \).
Simplify the complex fraction by multiplying numerator and denominator: \( \frac{\cos^{2} t}{\sin^{2} t} \times \sin t = \frac{\cos^{2} t \cdot \sin t}{\sin^{2} t} = \frac{\cos^{2} t}{\sin t} \).
Now, focus on the right-hand side (RHS): \( \csc t - \sin t = \frac{1}{\sin t} - \sin t \). To combine these terms, write \( \sin t \) as \( \frac{\sin^{2} t}{\sin t} \) to get a common denominator: \( \frac{1}{\sin t} - \frac{\sin^{2} t}{\sin t} = \frac{1 - \sin^{2} t}{\sin t} \).
Use the Pythagorean identity \( 1 - \sin^{2} t = \cos^{2} t \) to rewrite the numerator, so the RHS becomes \( \frac{\cos^{2} t}{\sin t} \), which matches the simplified LHS, thus verifying the identity.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.
Durata del video:
5m

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Trigonometric Identities

Trigonometric identities are equations involving trigonometric functions that hold true for all values within their domains. Verifying an identity means showing both sides of the equation are equivalent by using known identities and algebraic manipulation.
Video consigliato:
Percorso guidato
5:32
Fundamental Trigonometric Identities

Reciprocal and Quotient Identities

Reciprocal identities relate sine, cosine, and tangent to their reciprocal functions cosecant, secant, and cotangent. For example, csc t = 1/sin t and cot t = cos t / sin t. These identities help rewrite expressions to simplify or verify equations.
Video consigliato:
Percorso guidato
03:40
Quotients of Complex Numbers in Polar Form

Algebraic Manipulation of Trigonometric Expressions

Simplifying or verifying identities often requires factoring, combining fractions, and using common denominators. Careful algebraic steps allow transforming one side of the equation into the other, confirming the identity's validity.
Video consigliato:
Percorso guidato
6:36
Simplifying Trig Expressions