# What is the Cartesian form of ( -2 , ( - 9pi)/2 ) ?

Oct 26, 2017

The Cartesian point is $\left(0 , 2\right)$

#### Explanation:

Given: $r = - 2 \mathmr{and} \theta = \frac{- 9 \pi}{2}$

For the x coordinate, use the equation:

$x = r \cos \left(\theta\right)$

$x = - 2 \cos \left(\frac{- 9 \pi}{2}\right)$

$x = 0$

For the y coordinate, use the equation:

$y = r \sin \left(\theta\right)$

$y = - 2 \sin \left(\frac{- 9 \pi}{2}\right)$

$y = 2$

The Cartesian point is $\left(0 , 2\right)$

Nov 3, 2017

$\left(0 , 2\right)$

#### Explanation:

It can be seen from the diagram that the x coordinate of P is $r \cos \left(\theta\right)$ and the y coordinate of P is $r \sin \left(\theta\right)$

So:

$x = r \cos \left(\theta\right)$

$y = r \sin \left(\theta\right)$

From example:

$x = - 2 \cos \left(\frac{- 9 \pi}{2}\right) = 0$

$y = - 2 \sin \left(\frac{- 9 \pi}{2}\right) = 2$

Cartesian coordinate:

$\left(0 , 2\right)$