What is the Cartesian form of $( 13 , (-9pi)/4 )$ ?

Question

1421 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2015-12-26T02:48:26

First, find the coterminal angle for $(-9pi)/4$

coterminal angle $=4pi-(9pi)/4=(7pi)/4$

$(7pi)/4$ is in quadrant IV , so x is positive and y is negative .

$x=13cos((7pi)/4)=13sqrt2/2$

$y=13sin((7pi)/4)=13(-sqrt2)/2$

Cartesian Form $=(6.5sqrt2, -6.5sqrt2)$

hope that helped

What is the Cartesian form of ( 13 , (-9pi)/4 ) ( 13 , (-9pi)/4 ) ?