There is a mistake, but thats not it.
Base = sqr(R2^2+S2^2-2R2S2Cos(180 - Theta1))
But since Cos(180 - Theta1) = - Cos(Theta1)
Then
Base = sqr(R2^2+S2^2+2R2S2Cos(Theta1))
No Typo!
:)
Now, I checked it out 2 more times, by hand, and found a mistake
Towards the end. I'll fix the graphic, and then I'll do a test in a scratch progie.
BTW, Now I think the answer is 22.
:)
