Co-ordinate axes are rotated through an angle of 45∘ in the anti-Clockwise direction. Find the Co-Ordinates of (2,3) in new co-ordinate system.
Rotating the co-ordinate axes through an angle of 45∘ in anti-clockwise direction is equivalent to rotating the point through an angle of −45∘ about origin.We will use rotation from complex numbers to solve this.
Let x + iy the new complex number
x + iy = (2+3i)e−iπ4
= (2+3i)(1−i√2)
= (2 - 2i + 3i + 3)×1√2
=(5 + i) ×1√2
⇒(5√2,1√2) is the co-ordinate system.