Be careful when you use the law of sines! Whats sin(18 deg)? & more! Chegg Precalculus Office Hours @blackpenredpen

Uploaded March 2025 | Updated September 2026, 2 weeks ago

Chegg is hosting live office hours every week! The schedule is on our YouTube community page and stay connected with us here: che.gg/3E2AZRw

Today we will start with why you should be careful when you use the law of sines but there's no worries when you use the law of cosine. We will also convert a linear equation y=3x-1 into a polar equation. We will see how to write all trig functions in terms of just sine and more!

#blackpenredpen #chegg #math

0:00 Why we should be careful with the law of sines
17:52 Convert a Cartesian equation to polar
21:51 Solving 4cos^2(x)=3
34:15 Evaluating the exact value of sin(18 degrees)

Be careful when you use the law of sines! Whats sin(18 deg)? & more! Chegg Precalculus Office Hours

$First time solving an A-Level maths exam! (90 minutes, uncut) I will be doing a British A-Level further maths paper on the spot for the first time! This paper contains mainly algebra and calculus. Topics include complex numbers, hyperbolic equations, exponential equations, trigonometric identities and equations, first-order linear differential equations, determinant and the inverse of a 3x3 matrix, and more! Was I able to solve all the questions within 90 minutes? Was I able to get all the questions correct? Watch to find out. The afterward https://youtu.be/9GFUyT-D6D0 Try the paper first: https://qualifications.pearson.com/content/dam/pdf/A-Level/Mathematics/2017/Exam-materials/9fm0-01-que-20220526.pdf Big thanks to my Patrons for the full-marathon support! Ben D, Grant S, Erik S. Mark M, Phillippe S., Nicole D. 💪 Support this channel and get my math notes by becoming a patron: https://www.patreon.com/blackpenredpen 🛍 Shop my math t-shirt & hoodies: https://amzn.to/3qBeuw6 Timestamps: 0:00 A-Level further math paper from June 2022 0:58 Q1 Solving a cubic equation with complex roots 6:23 Q2 Solving a 4-th degree hyperbolic equation 15:55 Q3 Solving a first-order linear differential equation with integrating factor 21:28 Q4 Solving a series problem with natural log 28:55 Q5 Finding the determinant and the inverse of a 3x3 matrix Correction to Q5: https://youtu.be/pXdEBA6xI1c?si=11CZl3RkNheQQvMR 40:50 Q6 Partial fraction decomposition & integral of a rational function 50:05 Q7 A complex number problem 1:00:11 Q8 A long trig identity 1:23:39 Q9 An improper integral with hyperbolic cosine$

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$the first 5 days of calculus 2 but the integrals get harder! Learn more calculus on Brilliant (now with a 30-day free trial): 👉https://brilliant.org/blackpenredpen/ (20% off with this link!) Today we will see what your first 5 days in your calculus 2 or AP calculus BC class is like. Calculus 2 is known as integral calculus and we usually start with learning all the integration techniques. We will cover the integral of x^2 with the reverse power rule, the integral of x*e^(x^2) with u-substitution, the integral of x^2*e^x with integration by parts, the integration of sqrt(1+x^2) with trigonometric substitution, and the integration of (2x+1)/(x^2+3x+2) with partial fraction decomposition. 0:00 day 1, reverse power rule 0:20 day 2, u sub 1:27 day 3, integration by parts 2:29 day 4, trig sub 6:16 day 5, partial fraction decomposition 8:51 Check out Brilliant 🛍 Shop my math t-shirt & hoodies: amzn.to/3qBeuw6 💪 Support the channel and get featured in the video description by becoming a patron: https://www.patreon.com/blackpenredpen AP-IP Ben Delo Marcelo Silva Ehud Ezra 3blue1brown Joseph DeStefano Mark Mann Philippe Zivan Sussholz AlkanKondo89 Adam Quentin Colley Gary Tugan Stephen Stofka Alex Dodge Gary Huntress Alison Hansel Delton Ding Klemens Christopher Ursich buda Vincent Poirier Toma Kolev Tibees Bob Maxell A.B.C Cristian Navarro Jan Bormans Galios Theorist Robert Sundling Stuart Wurtman Nick S William OCorrigan Ron Jensen Patapom Daniel Kahn Lea Denise James Steven Ridgway Jason Bucata Mirko Schultz xeioex Jean-Manuel Izaret Jason Clement robert huff Julian Moik Hiu Fung Lam Ronald Bryant Jan Řehák Robert Toltowicz Angel Marchev, Jr. Antonio Luiz Brandao SquadriWilliam Laderer Natasha Caron Yevonnael Andrew Angel Marchev Sam Padilla ScienceBro Ryan Bingham Papa Fassi Hoang Nguyen Arun Iyengar Michael Miller Sandun Panthangi Skorj Olafsen Riley Faison Rolf Waefler Andrew Jack Ingham P Dwag Jason Kevin Davis Franco Tejero Klasseh Khornate Richard Payne Witek Mozga Brandon Smith Jan Lukas Kiermeyer Ralph Sato Kischel Nair Carsten Milkau Keith Kevelson Christoph Hipp Witness Forest Roberts Abd-alijaleel Laraki Anthony Bruent-Bessette Samuel Gronwold Tyler Bennett christopher careta Troy R Katy Lap C Niltiac, Stealer of Souls Jon Daivd R meh Tom Noa Overloop Jude Khine R3factor. Jasmine Soni L wan na Marcelo Silva Samuel N Anthony Rogers Mark Madsen Robert Da Costa Nathan Kean Timothy Raymond Gregory Henzie Lauren Danielle Nadia Rahman Evangline McDonald Yuval Blatt Zahra Parhoun Hassan Alashoor Kaakaopuupod bbaa Joash Hall Andr3w11235 Cadentato Joe Wisniewski Eric Maximilian Mecke Thank you all!$

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Be careful when you use the law of sines! What's sin(18 deg)? & more! Chegg Precalculus Office Hours