I’m sure you’ve been wondering since you first heard about radian measure before calculus why calculus is always done in radian measure. Once you’ve learned the derivatives of the trigonometric functions, you will appreciate why radians are pretty much the only choice for calculus people.
The idea for this series of posts, The Why Series, a this post I wrote a few years ago called “Why Radians?” The post gets a lot of ‘hits’ every year. While that post was written for teachers, there is no reason you, a student, shouldn’t read it as well; it’s not a secret. Or maybe it is, but now that you’re initiated into calculus, you may read it.
If you’re still wondering why calculus people use radians, follow this link: Why Radians?
AP Calculus Course and Exam Description Unit 2 Section 7.
Teaching Calculus 
Hi Lin, your blog is very practical. I’m not a student, but a math enthusiast who has been spending the last 9 months teaching myself Trigonometry, Calculus 1 and Calculus 2. I find self-study to be the most effective for me. I’d like to continue on to Calculus 3 and Differential Equations at some point in the future. I find calculus fascinating and have gained a new appreciation for numbers. If you have any tips for self-learners like myself, please let me known.
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Frieda
Sorry to take so long getting back to you; I’ve been out of town. Teaching yourself calculus – Wow! Good for you. I have no particular tips for you. You apparently found a way that works for you. There are plenty of sites online with lesson and instruction. If you’ve found a good one or two keep with it.
Keep up the good work.
Lin
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Thank you, Lin. It’s been a very enjoyable and satisfying process. Kind regards, Frieda
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