Look through it to make sure I don't make a mistake myself!
___________________< water lvl
|..\)8 degrees
|^..\
|*A..\ 2.6 ok so submarine go down @ 8 Deg's for 2.6 miles
X........\ miles
|............\
|...............\
|_____.....\
2 FIND X, u find 90-8 to get < A (I called it *A, it means angle A). 90-8 is 82, which is < A.
___________________< water lvl
|\)8 degrees
|^\
|82\ 2.6
X........\ miles
|............\
|...............\
|_____....\
Now, you just CohSahToa your way out of it. You'll use Sine (sah, adjacent/hypotenuse). so sin(82)=X/2.6 times 2.6 all around
sin(82)*2.6=X .
I got 2.5746969787280828192178146550966.. rounded to 2.57.
(not 2 scale)