Using sum and difference formula to find the exact value with cosine

Dude, I'm in college Trig right now and I am STRUGGLING. My professor doesn't explain the logic behind anything and the textbook videos aren't much better. Your videos are the reason I've understood most of what has been taught in the class. I can't thank you enough.

That feeling when he uses the exact problem you've been given. 🥰

I sat in my chair for 3 hours trying to figure this out.. 1:35 ... holy crap! Thanks!

There are no bad questions from someone whose never seen it, wish he didn't sorta snub her, that deters people from asking questions in the future

lol nooo dont loose your patience with that person. i needed that answer example ti finish my homework lol.

For anyone wondering how he got the (pi/3 + pi/4)
How I got it is pick a point on the unit circle, such as pi/3 or pi/4 (it helps to memorize the unit circle) and minus that by 7pi/12.
So I'll pick pi/4 because from memorizing the unit circle I know that we can subtract and get the 2nd value
1.) 7pi/12 - pi/4
1a.) pi/4 -> becomes 3pi/12 we need equal denominators to subtract from 7pi/12
2.) 7pi/12 - 3pi/12 = 4pi/12
2a.) simply 4pi/12 and you get pi/3
3.) you can verify that the values
pi/4 pi/3 and by adding both and you will get 7pi/12
I appreciate brian Logan saying not to worry about getting the 2 sums or difference to get the ball rolling but eventually this will catch up with you and you will have a gap in your knowledge. I can't think intuitively like that in math so I find this sort of algorithmic way to find the values.

He is a wonderful prof, makes life easy. Makes solving math problems piece of cake :)

in 10th grade in highschool and my teacher in algebra 2 sucks. this dude helps so much. i know this is 8 years later, but thank you 🙏🙏

Exam tomorrow and you helped me understand this type of problem thank you 😅😅

im curious what level you are teaching at?? i wish my professor would be this thorough on explanations but we're always strapped for time.. she just seems to blaze through topics.. and right as i make sense of it, she moves to the next topic. I
really appreciate all the effort and time it took to make this channel tho .. youve helped me immensely in my trig class.. ​ Brian McLogan

I still dont get it

Found the video on radians! Great job! Im not sure if you are a teacher or professor, but either one you teach very well!! 😬😅

THIS MAN IS A GIFT FROM GOD BLESS YOU GOOD SIR

Can we convert that from rad to degrees and solve using trig sum or difference formulas??
Say: cos(60 + 45) = cos60cos45 + sin60sin45 and then use the special triangles??
My test is tomorrow so you probably wont see this on time :)

How will you do cos(Pi/16) ? It’s a decimal value so it isn’t on the unit circle

you're a lifesaver !! thank you so much

Why am I a junior in high school learning this 🥺

Thank you!

is there a way to memorize the subtraction/addition formulas for sin/cos/tan?

What if it is negative? Cos-(7π/12)?

Lot of videos on easy problems. Why no video on hard problems - e.g. how to calculate sin π/17 ?

can you show how to solve it by converting to degrees please?

YOU MAKE IT EASIER! THANK YOU SO MUCH!

Heres an easy way to find the two additions if you have to:
If you had 7pi/12 like in this example, just do
Api/12 + Bpi/12 = 7pi/12
You have to find numbers that are divisible by 12 that also add upto 7, so its a bit of mental math here but its never too bad
I know 2pi/12 and 5pi/12 add upto 7pi/12 but 5pi/12 *isnt divisible by 12* so dont use that pair.
I know that 3pi/12 and 4pi/12 equal 7 and both numbers are also divisible by 12 so it works.
Simplify and you get pi/4 and pi/3 which are your special triangles and useful for finding exact values

زۆر سوپاس مامە گیان، ڤیدیوێکی بەسوودە

Thanks for this but plz make a video of sin2 360.

Didn't understand where the addition terms came from and you helped me big time

why did the sign chage though?

Never mind it works

its actually 105 degrees, not 95 degress as he said

I got scared bc he said my name when he did the U and V bc i dont do them lol.

I think your pi/3 should be 3pi/8 and your pi/6 should be pi/8 in your sketch.

Plzzz sin 2tita÷5

Eeeeyeaah next video

your thumbnail looks funny xD

you lost me at the start

India

Do you get paid extra for these videos?

One of the very few videos I’ve disliked. Most videos are more so for people as slow as I am, and there are an unusual amount of assumptions in this one. Assuming students catch on or follow you at the snap of a finger made me feel bad, as I’ve never really been good with math. But I am trying. Nonetheless, I still appreciate the attempt!

If I didn't have a clue of math, I probably wouldn't understand this teacher. Lmao! Just saying.

im in 8th grade doing this

It seems like he have no patience and a nasty sarcasm. He should be happy someone is asking questions and wants to learn no matter how many times you've repeated it. My opinion.

Ha lol