What are all the exact solutions to the equation (2 …

Mathematics Questions

Which shows all the exact solutions of 2sec^2x-tan^4x=-1 ? Give your answer in radians.

Short Answer

The process begins by understanding the tangent function and Pythagorean identities, which aid in transforming the equation 2sec¬¨‚â§x – tan‚ÄöA¬•x = -1. By rewriting it with Pythagorean identities, the equation simplifies to y¬¨‚â§ – 2y – 3 = 0, leading to valid solutions for y and ultimately yielding x = ¬¨¬±≈ìA/3 + n≈ìA as the final solutions in radians.

Step-by-Step Solution

Step 1: Understand Tangent Function and Pythagorean Identities

The range of the tangent function includes all real numbers, which is crucial for solving trigonometric equations. Begin by noting the essential Pythagorean identities, which are:

  • sin¬¨‚â§(≈í‚àè) + cos¬¨‚â§(≈í‚àè) = 1
  • 1 + tan¬¨‚â§(≈í‚àè) = sec¬¨‚â§(≈í‚àè)
  • 1 + cot¬¨‚â§(≈í‚àè) = csc¬¨‚â§(≈í‚àè)

Using these identities helps simplify your solutions for trigonometric equations. The given equation is 2sec¬¨‚â§x – tan‚ÄöA¬•x = -1.

Step 2: Transform the Equation Using Pythagorean Identities

Apply the second Pythagorean identity to rewrite the equation. Substitute sec²x in terms of tan²x:

  • Rewrite as: 2(1 + tan¬¨‚â§x) – (tan¬¨‚â§x)¬¨‚â§ = -1
  • Which simplifies to: (tan¬¨‚â§x)¬¨‚â§ – 2tan¬¨‚â§x – 3 = 0

Let y = tan¬¨‚â§x and change the equation to: y¬¨‚â§ – 2y – 3 = 0. Factor it to find the possible values of y.

Step 3: Solve for x Using Found Values of y

From the factored equation, you derive (y + 1)(y – 3) = 0, leading to y = -1 (not valid) or y = 3 (valid). Hence:

  • Since y = tan¬¨‚â§x = 3, then tan(x) = ¬¨¬±‚Äöao3.
  • Thus, x = tan‚ÄöA¬™¬¨œÄ(¬¨¬±‚Äöao3) gives solutions in degrees: x = ¬¨¬±60¬¨‚àû + n≈ìA.

Finally, convert degrees to radians to conclude that the solutions are x = ¬±œA/3 + nœA, for n in ‚N§.

Related Concepts

Tangent Function

A trigonometric function that represents the ratio of the opposite side to the adjacent side in a right triangle; its range includes all real numbers.

Pythagorean Identities

A set of fundamental relationships in trigonometry that relate the squares of the sine, cosine, tangent, secant, cosecant, and cotangent functions, helping to simplify trigonometric equations.

Secant Function

A trigonometric function defined as the reciprocal of the cosine function; sec²x is often used in conjunction with other trigonometric identities to solve equations.

Scroll to Top