Convert theta = 3pi/4 to rectangular form

Ф = 3π/4. Transform it into Rectangular (or Cartesian) form .The coordinates of Ф are x ,y  in rectangular form ==> so:tan(Ф) = y/x and y=x . tan(Ф) ==> y= x. tan(3π/4). we know that tan(3π/4)= - 1Hence y = - x

Answer:Here, Theta is Replaced by Angle A.[tex]A=\frac{3\pi }{4}[/tex]Suppose any point on the two dimensional coordinate plane is (r,A).Where A is angle made by line with positive direction of x axis and r is distance from Origin to that point.Projection of point on X and Y axis  and then converting to Rectangular form[tex]x=r Cos A, y=r Sin A\\\\ \frac{y}{x}=\frac{Sin A}{CosA}\\\\ y= x tan A\\\\ y=x* tan{\frac{3\pi}{4}[/tex][tex]y=x \times (-1)\\\\ y=-x[/tex]→y= - x is representation in Rectangular form of [tex]theta=\frac{3\pi }{4}[/tex]