Question

can you explain me this? (ill post to down)

Answer 1

\[da=\int\limits_{\theta=0}^{\pi}\int\limits_{\phi=0}^{2\pi} r^{2} \sin \Theta d \Theta d \phi\]

Answer 2

its simple

Answer 3

your limits are around the wrong way though lol

Answer 4

since you dont integrate with respect to r, you can treat it as a constant and pull it outside the whole integral

Answer 5

also, since your limits of theta and phi do not have any variables in them ( ie . the region of a integration is a rectangle ) , you can split it into a product of integrals

Answer 6

oO

Answer 7

\[= r^2 \int\limits_{0}^{2\pi}d \phi \int\limits_{0}^{\pi} \sin \theta d \theta\]

Answer 8

now looks like simple...

Answer 9

fairly sure its 4 pi r^2

Answer 10

this is for a sphere