The curve xy = - 1 is obtained by rotating 45 ° anticlockwise around the coordinate origin

The curve xy = - 1 is obtained by rotating 45 ° anticlockwise around the coordinate origin

Let a (x1, Y1) be on the curve xy = - 1, then it satisfies x1y1 = - 1. When the curve xy = - 1 rotates 45 ° counterclockwise around the origin of coordinates, and the coordinates of a 'point are (X2, Y2), then x2 = x1cos45 ° - y1sin45 ° = √ 2 / 2x1 - √ 2 / 2y1y2 = x1sin45 ° + y1cos45 ° = √ 2 / 2x1 + √ 2 / 2y1. The equations are: X1 = √ 2 / 2 (x2 + Y2