Question

Find the acute angle of rotation a that eliminates the xy term of x^2+4xy-3y^2-2x+y-6=0.

a.) 45°
b.) 60°
c.) 30°
d.) 22.5°

Answer 1

See if this helps - http://en.wikipedia.org/wiki/Rotation_of_axes#Elimination_of_the_xy_term_by_the_rotation_formula