Trigonometry

How to solve

Dividing sin² + cos² = 1 by cos² gives the tangent-secant identity — no angle needed, just the identity.

Steps

  1. Square the given value.
  2. Add or subtract 1 per the identity.
  3. Leave the answer as an exact fraction.

Example

tan θ = 3/4. Find sec²θ.

  1. tan²θ = 9/16.
  2. sec²θ = 1 + 9/16 = 25/16.

Answer: 25/16

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