If the tangent to the ellipse x2+4y2=16 at P(θ) is normal to circle x2+y2−8x−4y=0. Then θ equals to
π2
π4
0
−π4
Equation of tangent at P(4cosθ,2sinθ) is xcosθ+2ysinθ=4 It passes through (4, 2) ∴sinθ+cosθ=1∴θ=0,π2