What is the Cartesian form of $( -1 , ( 15pi)/4 )$ ?

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Answer 1 · 2017-10-25T12:52:31

$( -0.71 , 0.71 )$

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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:

$x=-1cos((15pi)/4)=-0.71$ (2 .d.p.)

$y=-1sin((15pi)/4)=0.71$ (2 .d.p.)

Cartesian coordinate:

$( -0.71 , 0.71 )$

What is the Cartesian form of ( -1 , ( 15pi)/4 ) ( -1 , ( 15pi)/4 ) ?