1. ## I feel so bad...but i have no choice

I feel bad about asking you for help all the time but i have no one else to turn to (except for a professor who sucks) and i have spent my day trying to solve this and several other trig-problems.

I am to find when some of these alternatives below cos x+ sin x=0 I have already tried with a calculator and it almost always comes out wrong and it takes ages to try all the options, the profossor doesn't explain anything and expects me to know this trigonometry crap without any previous experience.

Help is as always very much appreciated!

2. ## Re: I feel so bad...but i have no choice

I can't help but wonder why you posted this. You understand, don't you, that most of the people who post or respond here are themselves mathematics majors if not professors? But you refer to trigonometry as "crap" and complain about professors who actually expect you to know the pre-requisite material. You are given five possible solutions and complain that it "takes ages to try all the options". Actually, it takes about 5 seconds to check each one so less than half a minute to check all.

In any case, one of the very first things you should have learned about sine and cosine is the where they are positive and where they are negative- and that's all you need to know to solve cos(x)= -sin(x). The precise values are irrelevant.

3. ## Re: I feel so bad...but i have no choice

I apologize for that, i can understand that you found it disrespectful but, i have had no indept explaination of trigonometry in the past, i just use these formulas that the professor gave me for sin cos tan but i don't really understand why i use them, therefor i don't understand the basics and i get it mixed up very easily. For example cos(x)= -sin(x) is something i didnt know about before.

But now that i know this il try to do it again.

4. ## Re: I feel so bad...but i have no choice

There is no problem asking for help: it's why we are here. But it is probably advisable not to vent your frustrations while asking for help.

I have real sympathy for anyone who is merely asked to memorize formulas. Khan Academy Trigonometry is one place to get an explanation of the subject.

5. ## Re: I feel so bad...but i have no choice

$\displaystyle sinx + cosx = 0 sin x = -cos x tan x = -1$

Can you take it from here?