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Problem 11 - Entrance Test

If sec θ + tan θ = p, then sec θ - tan θ is equal to:

Correct: A

We know the trigonometric identity: sec² θ - tan² θ = 1. This identity can be factored as a difference of squares: (sec θ - tan θ)(sec θ + tan θ) = 1. Given that sec θ + tan θ = p, substitute this into the factored identity: (sec θ - tan θ)(p) = 1. To find sec θ - tan θ, divide both sides by p: sec θ - tan θ = 1/p.