If (cos θ + sec θ) = 5/2, then (cos2 θ + sec2 θ) = ?

Given: cos θ + sec θ = 5/2


Squaring both sides, we get:


cos2 θ + sec2 θ + 2 cos θ sec θ = 25/4


cos2 θ + sec2 = (25/4) – 2 cos θ sec θ


= 25/4 – 2


= (25 – 8)/4


= 17/4

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