IB Math AA SL: Calculus Review (Part 1 of 2, Analysis and Approaches, Standard Level)

[@ZachAR3]

For 17:54 you can get your starting fraction by just dividing your original e^whatever by the differentiation of its exponent, this also works in reverse so if your differentiating it you just multiply by the differentiation of the exponent.

[@mrp3347]

The real question is when are you going to start doing videos on HL content haha. Great videos, I appreciate it. 🙏🙏

[@sofiathorsson4212]

In around minute 43:00 you have cos(3pi/4) and you write it as (-root 2)/2. When looking at the quarter circle (pi/4) is (root2/2) but what happened to the 3 that was there. I understand that cos(pi/4) is (root2/2) but I don't get how cos(3pi/4) becomes (-root2/2). Your videos really help by the way, thank you!!

[@mathsl1]

The cosine of 3pi/4 (or 135 degrees) is negative because it's an obtuse angle. In standard position, it would be an angle that ends up in the second quadrant. Since cosine of an angle is the x-value of the corresponding spot on the unit circle, it's negative in quadrant II. (All trig ratios are positive in Q1, Sine is positive in Q2, Tan is positive in Q3, and Cosine is positive in Q4). Hope that helps! If not, check out around 9:10 in this video: kzbin.info/www/bejne/nJy9fJlnmbt7apo .