Using Sum and Difference Formulas in Trigonometry (Precalculus - Trigonometry 26)

How to use the Sum and Difference Formulas to find angles in Trigonometry including Inverse Trig functions, Unit Circle applications, and proofs of phase shift identities for Sine and Cosine.

[sseptemm]

I wish I had discovered you when I was a freshman, not just for grades, but for calculus.

[lamsam]

It’s good to see back Sir.

Salute to the Goat!

[kickinwing]

Oh boy, i caught an early video. Just wanna say that I appreciate your lectures for Calc 3! wish i found these back in calc 2. Keep up the great work!!!

[briangale]

Your online lectures are a great supplement to my calculus class. I definitely needed a refresher in Trig. Thank you.

[georgesadler]

Professor Leonard, thank you for another outstanding video/lecture on Using Sum and Difference formulas in Trigonometry. These are well known and fairly simple formulas in old fashion Trigonometry. They are constantly used in Math and Science.

[bennieholcomb]

Just joined your Patreon. I look forward to learing everything you can offer. Keep up the good work.

[dhpwuzd]

I watched all your videos for clac1, 2, and 3. You saved my GPA. Thank you so much. BTW, I will be graduating next semester with BS in electrical and computer engineering

[ericb]

Schools should really start teaching trig in terms of x, y, and r because everything goes back to the foundation of Geometry and the unit circle. This would be much more cohesive in curriculum order as opposed to learning SoH-CaH-ToA as a
mnemonic device which personally can be time-consuming. We already associate "x" with cosine and "y" with sine... it just makes sense and is much more clear. Great video and insight here & in the last video. 👍

[austinchandler]

Woah you've changed haha I've been watching your calc 3 lectures. You're a great professor, keep it up!

[zack_]

16:35 - why using right arrows in the equation? Using '=' is perfect: accurate and succinct.

36:03 - now it is a puzzle that sin⁻¹(1/2) = arcsin(1/2) ≠ csc(1/2) 😂

[vmxdyxp]

51:16 Is there a way to figure out what angle that is aside from putting it in a calculator? The angle is 120.51023..., but any way to figure that out on paper?
Btw, Im loving your teaching. Its super methodical and detail oriented.
Thanks Brofessor

[therandomperson]

for each set of topics, can you make videos of their applications? Or when you are giving problems to practice, they can be real-world scenarios. I don’t really know when I’ll use higher degree polynomials in the 5th or 6th degree or the complicated rational-functions in high degrees.

[quant-prep]

when's the linear algebra starting ?? Anyone know about that ?
Howmuch videos left to finish trigonomtry?
anyone give me some approximations please ?