Mathematical Question concerning Firing Solutions - what am I doing wrong?

[HMS Vanguard]

Hey,

Okay, so I'm sitting in the training mission for torpedo runs, and I'm attempting to develop the skills in trigonometry to manually work out firing solutions on the Cruiser that sails across my bow. I'm using the process put forward in the excellent thread "http://www.subsim.com/radioroom/show...ghlight=manual" by starvingartist507, but I'm running into a snag with my calculations, and being aware of my general poor maths skills I was wondering if someone could show me where I'm going wrong?

The problem I am having is when I get to Step 4:
"4. Subtract the first total (step 1) from the second total (step 3) 339,860
(8,840,000-8,500,140)"

This is subtracting the total of A Squared + B Squared from the total of "2 x (Cos of Bearing Change) x Range 1 (R1) x Range 2 (R2)". The problem I am having when calcuating the solution is that the total of the former is larger than the total of the latter. As an example:

On the latest time I've attempted the firing solution, my two readings were Bearing 325 at 1,357 feet, and Bearing 342 at 1,242 feet, timed at 45 seconds with a bearing change of 17. The total of R1 Squared + R2 Squared was 3,384,013.

The Cos of 17 turned out to be 0.257, and 2 x 0.257 x 1357 x 1242 = 926,966.7. Subtracting 3,384,013 from 926,966.7 results in -2,457,046, which as a negative number cannot be turned into a square root according to my calculator.

What am I doing wrong here? Any help would be appreciated in this, so I can get to sinking.

Good hunting!