Which Pythagorean identity is correct?

The Pythagorean identity involving tangent and secant is tan²(θ) + 1 = sec²(θ). Therefore, choice B, “tangent squared of theta plus 1 is equal to secant squared of theta,” is correct. The other choices do not match the standard identities: for example, 1 − cos²(θ) equals sin²(θ), not tan²(θ).

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