what is an equation of the conic section x^2+y^2=16 after a rotation of 45 degrees about the origin.

Question

A. (x')^2+(y')^2=16
B. (x')^2- (y')^2=16
C. (x')^2- 2x'y'+(y')^2=16
D. (x')^2+ 2x'y'+(y')^2=16

Answer 1

think. It's a circle. Invariant under rotation about its center.