∵x2+y2−2x−4y−20=0 After rotation of axes through θ=π∕4, it transforms to ax2+2hxy+by2+2gx+2fy+c=0 in the given equation a=1,h=0,b=1,g=−1,f=−2,c=−20 After rotation of θ=π∕4 ‌a′=acos2θ+bsin‌2θ+2h‌cos‌θ‌s‌i‌n‌θ ‌‌‌=1(‌
