6 more posts in this thread. [Missing image file: exercise 6.13.png]
any logic people on here?
I'm having a problem in my Language proof and Logic problems, chapter 6, using fitch. I need to prove
The pic is the proof that I made. It works all the way until the end, when I try to use Disjunction elimination to prove Dodec(f) by citing the Disjunction and the two sub proofs, but it tells me its not a proper application of the rule. Can any one see the problem that I made, and explain it to me? I've been having a lot of problems with disjunction Elim
Trig double angle equation help
9 more posts in this thread. [Missing image file: Inline11.gif]
Hey /sci/, I'm studying for a math test and am seriously stumped at one problem.
Find the (real) values for A, B and C for all values of x:
I know to start by expanding (5cos(x)-9sin(x))^2 into 81sin^2(x)-90cos(x)sin(x)+25cos^2(x), and use the double angle formulas from there. I can get the value for B easily, 45*2cosxsinx=45sin2x, and since it's negative B must equal -45. But I keep ending up wrong with A and/or C.
I know which formulas to use, but I don't seem to get how to use multiple formulas simultaneously. Please help me, /sci/, I've been stuck on this part for over a week now.