Math Problem Statement

Prove the identity: sec^2 x + csc^2 x = sec^2 x csc^2 x

Solution

To prove the identity sec2x+csc2x=sec2xcsc2x\sec^2 x + \csc^2 x = \sec^2 x \csc^2 x, let's break down the steps systematically.

Given Identity:

sec2x+csc2x=sec2xcsc2x\sec^2 x + \csc^2 x = \sec^2 x \csc^2 x

Steps:

  1. Rewrite secant and cosecant in terms of sine and cosine: secx=1cosx,cscx=1sinx\sec x = \frac{1}{\cos x}, \quad \csc x = \frac{1}{\sin x} Thus: sec2x=1cos2x,csc2x=1sin2x\sec^2 x = \frac{1}{\cos^2 x}, \quad \csc^2 x = \frac{1}{\sin^2 x}

  2. Substitute these into the left-hand side (LHS): 1cos2x+1sin2x\frac{1}{\cos^2 x} + \frac{1}{\sin^2 x} To simplify this, take the common denominator: sin2x+cos2xcos2xsin2x\frac{\sin^2 x + \cos^2 x}{\cos^2 x \sin^2 x}

  3. Simplify using the Pythagorean identity sin2x+cos2x=1\sin^2 x + \cos^2 x = 1: 1cos2xsin2x\frac{1}{\cos^2 x \sin^2 x}

  4. Compare the result with the right-hand side (RHS): The right-hand side is sec2xcsc2x\sec^2 x \csc^2 x, which can also be written as: 1cos2x×1sin2x=1cos2xsin2x\frac{1}{\cos^2 x} \times \frac{1}{\sin^2 x} = \frac{1}{\cos^2 x \sin^2 x}

Since both sides are equal, the identity is proved: sec2x+csc2x=sec2xcsc2x\sec^2 x + \csc^2 x = \sec^2 x \csc^2 x

Would you like further details or clarification on any step?

Here are 5 related questions to explore further:

  1. How do you derive the Pythagorean identity sin2x+cos2x=1\sin^2 x + \cos^2 x = 1?
  2. What are other important trigonometric identities similar to the one used here?
  3. How would you prove the identity tan2x+1=sec2x\tan^2 x + 1 = \sec^2 x?
  4. Can you solve this identity using a different method?
  5. How do you simplify trigonometric expressions involving multiple identities?

Tip: Always remember to convert complicated trigonometric expressions into sine and cosine to simplify proofs!

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Math Problem Analysis

Mathematical Concepts

Trigonometric Identities
Simplification of Expressions

Formulas

sec x = 1 / cos x
csc x = 1 / sin x
Pythagorean Identity: sin^2 x + cos^2 x = 1

Theorems

Pythagorean Identity

Suitable Grade Level

Grades 9-12