@athenanv13 For the first one, your answer is wrong. lim (x–>a) (cosx - cosa)/(x-a)
Taking the derivative of both top and bottom, I get: (-sinx + sina (0))/ 1 = lim(x–>a) -sinx = -sina I just figured out how they solved it in the book though. You forgot to put the negative in front of the sinx since deriv of cos is -sin.
@coffeeaddicted Yea I knew it was the definition of a derivative but I didn’t know how to apply it. I understand it now thanks!
13 Hours in Benghazi - Great Movie and even better Book.
Anybody have any tips on how to make more time to read books? There are lots of books I want to read (mostly political) but I can’t seem to make time between homework, ACT prep, and extracurriculars. Also, books are expensive. Any tips on saving money for them (I like to buy my books)?
@tigerman333 I usually read small portions of books that I’m interested in before bedtime, although I see how this wouldn’t be a viable option - especially since it seems that you’d be exhausted from preceding events in a day to retain the information from the book. You could also make it a priority - make it the first thing you do when you get home from school, and read small portions (i.e., 30 minute reading sessions) at a time. However, neither of these methods works particularly well if you’re interested in reading a book in one go (sorry about that!)
There are a few bookstores that are relatively cheap (Half-Price Books being one of them), and if you’re not worried about buying secondhand, I would recommend checking out your local library to see if they have sales on books (I’ve bought quite a few from a nearby library - a few dollars per book (at most, and the most expensive books are textbooks) or looking at eBay if trusting online sellers isn’t an issue. In terms of saving, I don’t know if you have a job, but if so, you could put a few dollars (two to five) of your paycheck or allowance (if you get one) toward books. I try to allot half of my allowance for saving, and the other half for spending; if you were to use a similar method, you could divide the spending portion into spending on books and spending on other necessities and/or whims.
Sorry if this wasn’t any help, but I hope you’re able to find the time (and the money) to continue reading for pleasure/interest while maintaining your grades & pursuing extracurriculars! 
On a totally different note, Half Price Books is amazing for finding foreign language books!
Edit:
@tigerman333 I read a bit in car rides, before bed, or during homework breaks. Regarding the second part, I definitely second what @desideratum said about Half-Price Books.
@desideratum Thanks for the ideas. I don’t have a job. I think I’m gonna put off reading till the summer.
I do however, love Half Price Books. It’s my go-to bookstore. The only problem is, they usually don’t have any of the newly released book. As a result, I end up going to Amazon and shell out $15-20. I think they need to increase their selection. They also pay nothing for buying your books.
I feel guilty when I read books. I would love to spend 30 minutes after school reading them, but then I’d feel like I could be studying for classes that I’m struggling in instead 
@GrandBudapest I feel you. You always get that thought that there is more important stuff you should be focusing on.
I used to just go on Netflix before I go to sleep, but I’ve opted to reading instead and it has helped me a lot with reading in my spare time. I usually read one to two chapters a night, it’s not a lot but it helps me relax before I go to sleep. Last year I would occasionally have trouble sleeping (there would be instances where I would only get three hours of sleep because I couldn’t sleep at all), but ever since I’ve replaced electronics with books I’ve had more sleep on school nights.
I did the same thing as @Greninja. I used to watch television all the time, and I still do because I love criticizing and analyzing tv shows. But I’ve moved towards reading a lot more books in my free time.
I’d recommend that when you have free time, pick up a book! At first, it was really difficult for me to read a lot because I kept feeling like I needed to annotate it because of my AP Lang teacher. Now, I spend at least an hour a day reading random books, I just have to schedule it properly. Although, I will say that I’m not a particularly committed student compared to some of y’all, so that may be why I have more time to read.
@foliontai I miss reading. All of this talk about reading got me to find and read out of a Literature Anthology book. 10/10 would recommend.
Random Question - Do colleges change their application essays from year to year? Because if not, I might as well begin working on them now or in the summer.
8th graders: Just say to hell with SAT/college prep stuff. If you actually want to do well, find something you like and do it at the expense of other things.
@jjlundy http://www.commonapp.org/whats-appening/application-updates/common-application-announces-2016-2017-essay-prompts I think this will help in terms of common app essays. Not sure about specific supplements from colleges though D:
@KinglyBill SIGHS YOU’RE RIGHT. Freshman year was actually my favorite because I didn’t feel pressured to take classes pertaining to a future major (although up until the beginning of this year, after I had already chosen classes for it, I didn’t know what I wanted to do with my life).
@KinglyBill Your comment reminds me of something from yesterday. My aunt held a small get together and her friend who has a seventh grade daughter attended. Talking to her daughter made me really sad - her mom’s forcing her to study SAT and ACT prep books, be in soccer competitions (a sport she doesn’t enjoy), and practice piano for an hour every morning with a teacher. It’s all very typical for a tiger mom, but it just made me sad that she’s wasting her time on things that she doesn’t care about… And this is 7th grade… Can’t even imagine what her life will be like in 11th grade…
Yeah, I’ve heard way too many stories like that. Thankfully my family doesn’t have that issue. My two brothers were the most - screw-wasting-time-on-stuff-i-don’t-like - students ever, and they ended up doing really well. But maybe they were smart; maybe that helped them succeed? IDK I still think parents should chill a bit.
@tigerman333 This is a late reply sorry! I’m interested in business and science (neuroscience and microbiology).
I’m mad at my school…we did not have a snow day and it’s snowing badly. I don’t mind going to school. I just mind when it’s super slippery on the roads and since I live in the mountainous region of Colorado, it’s scary going up and down hill