Formulas for Trigonometric Functions: Sum/Difference, Double/Half-Angle, Prod-to-Sum/Sum-to-Prod

There are tons of formulas we can learn that involve trigonometric functions. These help us evaluate trig functions for angles that are half of a common angle, twice a common angle, the sum or difference of two common angles, all kinds of stuff. They are a little annoying to learn but they are super useful so let's just bite the bullet and knock them all out in one clip!

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[OkSid]

Dave managed to combine everything I hate about math in one comprehension question. Roots inside of roots, Fractions over fractions, and formulas inside of formulas. Great work!

[tuhinshaikh]

it would be much help full if you can provide the formula chart

[UziMan-Science-Math]

7:03 We can actually express √ (2-√ 3)/2 as (√ 6 - √ 2)/4

[Atharv_Nigam]

Great video! it's easy to remember all the formulas but any idea of how they are derived ??

[habibaelhadad]

there is an error in the last question at the end of the video

[awesomeswordsman]

oh boy *cracks fingers* time to memorize another table of formulas

[gabriellegoddard]

THANK YOU SO MUCH YOUR A LIFE SAVER AND ENJOYABLE TO WATCH

[linuswalker]

In checking comprehension, the answer of second question (`cos 22.5`) should be the `sqrt((2+sqrt(2))/4)`, isn't it?

[RubbyLissam]

Is the formula Cos A + Cos B = 2 Cos

Or is it supposed to be Cos A + Cos B = 2 Sin

Which of the two correct?

[HellooDae]

For the last question, cos 105, I solved it like this:

cos pi/12 = (sqrt( 2 - (sqrt3) )) / 2 and it is the same as your answer except it gives a positive answer :/ could someone explain whether it is correct or not and why? (I am dumb)

[maheshgudipudi]

If this happened in my 12th I got the best rank in IIt 😢😅😊😊 that's why I hate youtube coz it recommended after 5years

[RubbyLissam]

Someone to answer me
In the case of Cos 105° in order to express 105 as (A+B), , can one take sum of any two numbers that add upto 105 eg: (100+5) or there is a specific way to find the two numbers

[hahahehe]

Matematika Peminatan kelas 11
Bab II: Jumlah Selisih Sinus Cosinus

[Aleksander_garcia]

i have a dude. whats the meaning of sqrt? 8:56