
evaluating integral
Evaluate the integral by interpreting it in terms of areas.
37. $\displaystyle \int^0_{3} (1+\sqrt{9x^2})*dx$
the answer is $\displaystyle 3+\frac{9}{4}*\pi$
Where .. the heck did $\displaystyle \pi$ come from?
I was trying to do
$\displaystyle \frac{ba}{n}$
$\displaystyle = \frac{03}{n}$
$\displaystyle =\frac{3}{n}$
and then $\displaystyle x_{i}$ as $\displaystyle \frac{3i}{n}3$
then plugging $\displaystyle x_{i}$ into $\displaystyle f(x)*dx$ then solving for the limit. It came out to be a super complicated root problem so I look in the back to see if I'm in the right track.. and theres a $\displaystyle \pi$ in the answer...
I think I'm missing something here... how is this integral end up having a $\displaystyle \pi$?

delete this

oops, must've clicked submit two times, how do i delete this? or do i need a moderator?

hit edit and look for where it says delete