If cosθ - sec θ = 3 , find the value of cos2θ + sec2θ .
Answer & explanation
Correct answer: option 3
Formula I → [ cosθ = \(\frac{1}{secθ}\)]
Formula II → [If x - \(\frac{1}{x}\) = n and x2 + \(\frac{1}{x^2}\) = n2 + 2]
cosθ - \(\frac{1}{cosθ}\) = 3
⇒ cos2θ + \(\frac{1}{cos^2θ}\) = (3)2 + 2
⇒ cos2θ + sec2θ = 9 + 2 = 11