<p>Given triangle ABC, C is a right angle.</p>
<p>sin(B-A) is equal to which of the following?</p>
<p>(A) (a^2-b^2) / (c^2)</p>
<p>(B) (a^2-b^2) / (a^2+b^2)</p>
<p>(C) (b^2-a^2) / (b^2+a^2)</p>
<p>(D) (c^2) / (b^2-a^2) </p>
<p>(E) (c^2) / (a^2-b^2)</p>
<p>I don't need an explanation, I just need the answer. I want to confirm a typo in a book :)</p>
<p>I got (b^2-a^2) / (c^2) , but that's not a choice.</p>
<p>But c^2 = (a^2+b^2), so wouldn't it be C?</p>
<p>Sin[B-A]=-Cos** Sin[A] + Cos[A] Sin**</p>
<p>=-[A/C] [A/C] + [B/C] [B/C]</p>
<p>=-A^2 / C^2 + B^2 / C^2</p>
<p>= [B^2 - A^2] / C^2</p>
<p>= [B^2 - A^2 ] / <a href="pythagorean%20theorem">B^2 + A^2</a></p>
<p>Thus, the answer is C.</p>
<p>Thanks :)</p>
<p>Sparknotes annoys me.</p>
<p>np!</p>
<p>sparknotes is annoying at times! because you have to read off the computer screen lol :D</p>
<p>I have the book. But still. I just took another practice test, and two of the four answers were identical :(</p>
<p>yeah i know.. i took an online test and a question refers to a diagram thats never there</p>
<p>OK, so on Saturday, I took one of their practice tests, and I (amaaaaaaaaaazingly) got an 800. And then I took another one yesterday, and got a 710 or something. What the heck is up with that??</p>
<p>....... you missed a couple questions when you took the 710. big deal..... maybe you got lucky on the first one?</p>
<p>It seemed totally different the second time...</p>
<p>For the first one, I made 6 errors, and 0 omission. I at least knew how to solve every single one.</p>
<p>But for the second one, I also made 6 errors, but also NINE omissions :(</p>
<p>well... not to point out the obvious, but the 9 omissions probably hurt.</p>
<p>but on you saying the tests were totally different, I think Math IIC covers a wide range of topics, therefore every once in a while the subject matter would be completely different.... or something of the sort.</p>
<p>It just seemed a whole lot harder, and I ran out of time a lot sooner, hence the 9 omissions. Maybe I just wasn't thinking that day, because usually when I skip a problem, then do the rest, and then go back to the skipped one, I can easily figure it out. But that obviously didn't happen that time :(</p>
<p>I should take a third test to see what happens, and just hope I don't continue the downward trend! haha</p>
<p>i suppose. good luck on future tests and the real thing.</p>
<p>Thanks :)</p>
<p>I wish spring break were longer.</p>