Math Problem Statement

Write an algebraic expression that is equivalent to csc(arccos(9/x)).

Solution

To solve this expression, we need to simplify csc(arccos(9x))\csc \left( \arccos \left( \frac{9}{x} \right) \right).

Let's go through the steps:

  1. Define the Angle: Let θ=arccos(9x)\theta = \arccos \left( \frac{9}{x} \right). This means that cos(θ)=9x\cos(\theta) = \frac{9}{x}.

  2. Find sin(θ)\sin(\theta): To express csc(θ)=1sin(θ)\csc(\theta) = \frac{1}{\sin(\theta)}, we need sin(θ)\sin(\theta).

    • Using the Pythagorean identity, sin2(θ)+cos2(θ)=1\sin^2(\theta) + \cos^2(\theta) = 1.
    • Substitute cos(θ)=9x\cos(\theta) = \frac{9}{x}:
      sin2(θ)+(9x)2=1\sin^2(\theta) + \left( \frac{9}{x} \right)^2 = 1 sin2(θ)+81x2=1\sin^2(\theta) + \frac{81}{x^2} = 1 sin2(θ)=181x2\sin^2(\theta) = 1 - \frac{81}{x^2} sin(θ)=181x2\sin(\theta) = \sqrt{1 - \frac{81}{x^2}}
  3. Find csc(θ)\csc(\theta): Now that sin(θ)=181x2\sin(\theta) = \sqrt{1 - \frac{81}{x^2}}, csc(θ)=1sin(θ)=1181x2\csc(\theta) = \frac{1}{\sin(\theta)} = \frac{1}{\sqrt{1 - \frac{81}{x^2}}}

Thus, the equivalent algebraic expression is: csc(arccos(9x))=1181x2\csc \left( \arccos \left( \frac{9}{x} \right) \right) = \frac{1}{\sqrt{1 - \frac{81}{x^2}}}

Would you like more details or have any questions?

Here are five related questions:

  1. How would this expression change if it were sec(arccos(9x))\sec(\arccos(\frac{9}{x})) instead of csc\csc?
  2. What if we had sin(arccos(9x))\sin(\arccos(\frac{9}{x})) instead of csc\csc?
  3. How does understanding trigonometric identities help in simplifying such expressions?
  4. Why do we use the Pythagorean identity in this simplification?
  5. Could we encounter similar expressions with other inverse trigonometric functions like arcsin\arcsin or arctan\arctan?

Tip: When dealing with inverse trigonometric functions, try assigning a variable to the angle, then use trigonometric identities to find equivalent expressions.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Inverse Trigonometric Functions
Trigonometric Identities

Formulas

csc(θ) = 1/sin(θ)
sin²(θ) + cos²(θ) = 1
cos(θ) = 9/x

Theorems

Pythagorean Identity

Suitable Grade Level

Grades 11-12