Is tan 2x sec 2x = 1 an identity?

To determine if the equation tan(2x) sec(2x) = 1 is an identity, we need to analyze both sides of the equation.

First, let’s recall the definitions of the tangent and secant functions:

  • tan(θ) = sin(θ) / cos(θ)
  • sec(θ) = 1 / cos(θ)

Applying these definitions to our equation:

tan(2x) = sin(2x) / cos(2x> and sec(2x) = 1 / cos(2x)

Substituting these into the left side of the equation leads to:

tan(2x) sec(2x) = (sin(2x) / cos(2x)) * (1 / cos(2x)) = sin(2x) / (cos(2x) * cos(2x))

Now, simplifying this further:

The expression simplifies to:


sin(2x) / cos²(2x)

For the right side of the equation, we have simply 1.

Now, we check if sin(2x) / cos²(2x) = 1.

This equation can be transformed into:

sin(2x) = cos²(2x)

This equality holds true only for specific values of x, rather than being true for all values, which means that tan(2x) sec(2x) = 1 is not an identity.

In conclusion, tan(2x) sec(2x) = 1 is not an identity as it does not hold true for all values of x.

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