- #1

yoleven

- 78

- 1

## Homework Statement

[tex]\int[/tex][tex]\int[/tex]

_{D}[tex]\left|x\right|[/tex]dA

D= X

^{2}+y

^{2}<=a

^{2}where a>0

## Homework Equations

[tex]\int[/tex][tex]\stackrel{\Pi/2}{0}[/tex][tex]\int[/tex][tex]\stackrel{a}{0}[/tex] r cos [tex]\Theta[/tex] r dr d[tex]\Theta[/tex]

I hope that's clear...

I evaluate this to [tex]\frac{a^3}{3}[/tex] sin [tex]\Theta[/tex]

sin [tex]\Pi[/tex]/2 = 1

so I get [tex]\frac{a^3}{3}[/tex]

the book says the answer is 4 [tex]\frac{a^3}{3}[/tex]

I can't see where the 4 is coming from.

can some one explain this to me?