What is the Cartesian form of $(91,(-13pi) /12)$ ?

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Answer 1 · 2017-10-18T17:18:44

$( -87.90 , 23.55 )$

enter image source here

It can be seen from the diagram that the x coordinate of P is $rcos(theta)$ and the y coordinate of P is $rsin(theta)$

So:

$x=rcos(theta)$

$y=rsin(theta)$

From example:

$( 91 ,( -13pi)/12 )$

$x=(91)cos((-13pi)/12)= -87.89925019= -87.90$ (2 .d.p.)

$y = (91)sin((-13pi)/12)= 23.55253310=23.55$ (2 .d.p.)

Cartesian coordinate is:

$( -87.90 , 23.55 )$

Polar Graph:

enter image source here

What is the Cartesian form of (91,(-13pi) /12)(91,(-13pi) /12)?