Question

If xcosα + ysinα = xcosβ + ysinβ = 2 lim_(n →∞) (aⁿ + bⁿ)^1/n (where x² + y² ≠ 0 and 0 < b < a), then

(A) cosα + cosβ = cosα cosβ is a parabola

(B) cosα + cosβ = sinα+ sinβ is a straight line

(C) cosα + cosβ = sinα sinβ are pair of line

(D) cosα cosβ + sinα sinβ  = 0 is a circle

Answer 1

Answer is (A), (B), (C), (D)

Equation (1) shows that α and β are the roots of x cosθ + y sinθ = 2a (2) 

Therefore,