[PreCalculus] Proving Identities

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SUMMARY

The identity to prove is (1 + cos² x) / sin² x = 2csc² x - 1. The left-hand side (LHS) can be rewritten as csc² x + cot² x using the identities 1/sin² x = csc² x and cos² x/sin² x = cot² x. By applying the fundamental trigonometric identities, the proof can be completed successfully. A recommended resource for further understanding is the website IntMath, which provides comprehensive insights into trigonometric identities.

PREREQUISITES
  • Understanding of trigonometric identities, specifically sin² x, cos² x, and their relationships.
  • Familiarity with the concepts of cosecant (csc) and cotangent (cot).
  • Ability to manipulate algebraic expressions involving trigonometric functions.
  • Knowledge of fundamental trigonometric equations such as cos² x + sin² x = 1.
NEXT STEPS
  • Study the derivation and application of the identity cot² x = csc² x - 1.
  • Explore the use of the Pythagorean identity in proving trigonometric identities.
  • Learn about the process of simplifying complex trigonometric expressions.
  • Review additional resources on trigonometric identities, such as the IntMath website.
USEFUL FOR

Students studying precalculus, mathematics educators, and anyone seeking to master trigonometric identities and their proofs.

Snowglober
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Homework Statement


Prove that this is an identity.

1 + cos² x / sin² x = 2csc² - 1

Homework Equations


cos²x + sin²x = 1 (manipulative equation)
tan²x = sec² - 1
cot²x = csc²x - 1
etc..

The Attempt at a Solution


I attempted this equation more than 10+ times. Each time, I find a way but I get half way there and it doesn't work out.
 
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Hi Snowglober, welcome to PF
The problem should be
(1 + cos^2x)/sin^2x = 2csc^2x - 1
Now LHS can be written as
1/sin^2x + cos^2x/sin^2
= csc^2x + cot^2x
Now use the identities to get the result.
 

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