Introduction to Sum and Difference Formulas in Trigonometry (Precalculus - Trigonometry 25)

What the Sum and Difference formulas are for the three basic trig functions, where they come from, and how to use them to find exact solutions to angles that are not on the Unit Circle.

[GhaliumHD]

I have finished all the calculus courses I have in my curriculum (Calc1 to differential equations), and I swear to God that the day I graduate from engineering and get a job, a portion of my first paycheck goes to Prof. Leonard. Thank you for everything!

[March_iii_]

You are the hidden gem in Trigonometry.

[jerrymorales]

Thank you for sharing your knowledge with us.

I watched your videos for Calc 1, Calc 2, Calc 3, and differential equations and got As in all four classes. Now I watch them just to learn more 🤓

[surojpaul]

100 lectures complete in precal., , take a bow🙌🙏

[onemanenclave]

Your teaching has become even smoother and clearer if that was possible.

[tbeng]

Hello professor Leonard, first of all wanted to thank you for bringing passion to Mathematics, I wanted to know is there any chance in the future you could do some more advanced stuff like Fourier Series, Laplace Transform, Complex integration etc. ? It could be really helpful for engineering students like myself.

[WhimsicalAlec]

Take trigonometry fully online and your videos have been so helpful! Thank you!

[georgesadler]

Professor Leonard, thank you for another beautiful video/lecture on the Introduction to Sum and Difference Formulas in Trigonometry. From reviewing this material, I found this material not too difficult, however it can be confusing or problematic. Using the Sum and Difference Formulas to solve problems is one way to master this topic.

[colchi]

I personally recommend 3Blue1Brown’s lockdown maths playlist for an intuitive derivation of these formulas using the complex plane

[raghavsood]

Sir thank you so much for posting these videos. Your videos really helped me a lot to understand the stuff on which I was struggling before.
Once again thank you so much

[willcartershaves]

Love your work man. I knew you’d always do something fantastic bro. Love your intelligence

[mohamedshahbain]

I didn't need precalc help I just clicked on the video to comment on that crisp fade

[TheMoresnow]

Dope! This topic just showed up in my physics class. Thanks man!

[arnaldoperez]

Can't wait to get into this level. I'm still in intermediate algebra playlist but I'll get here. Thank you Professor Leonard!

[Alel]

Wow, I just wanted a video to review this lesson, thanks for your hard work🌷

[anweshbhattacharyya]

Prof Leonard you are my guru 😌❤️. How does an exponential function differ from a power function ??
The essential difference is that an exponential function has it's variable in it's exponent, but a power function has its variable in its base. For example f(x)=3^x is an exponential function, but g(x) = x^3 is a power function.

[dhickey]

Thank you for your help and inspiration.

[Redexn]

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[francistde_menace]

looking good man, thanks for the video!

[GaryPwner]

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