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MathBySarah
Добавлен 17 янв 2012
I started this channel when I was teaching college math from the basics of pre-Algebra all the way through the Calculus series. I would like to make more videos. Message me if you have a video you would like an answer too.
I also help parents who want to know why they have to learn this "new math". I can explain the reasoning behind the a topic being introduced.
I have been working in the ML world for the last 4 years, and would be happy to research a topic and make a video about it. If you need help digging into something let me know and I might just be able to help you.
I also help parents who want to know why they have to learn this "new math". I can explain the reasoning behind the a topic being introduced.
I have been working in the ML world for the last 4 years, and would be happy to research a topic and make a video about it. If you need help digging into something let me know and I might just be able to help you.
Intro to extreme values, critical points, and closed interval test
Extreme Values, Absolute Max, Min. Closed interval test. critical points. Local max, min
Просмотров: 409
Видео
Free online graphing program for space curves
Просмотров 1808 лет назад
I am showing my students how to use the free online 3-D grapher that I found here: www.livephysics.com/tools/mathematical-tools/online-3-d-function-grapher/
Find the distance between skew lines
Просмотров 54 тыс.8 лет назад
In this video I define skew lines and go through the process of finding the distance between the two lines using the projection of a random vector connecting the two lines on to the normal vector of the two planes in which the skew lines exist.
Plane, Wind, Vector Problem
Просмотров 9 тыс.8 лет назад
This problem is a vector problem involving A plane heading North and wind from the NW pushing the plane off course. I investigate ways to get the magnitude and direction of the plane's resulting direction.
HW7#14: m*sin(Bx) + n*cos(Bx) = A*sin(Bx + C)
Просмотров 668 лет назад
Another example of writing a sum of a cosine function and a sine function with the same argument (stuff inside the trig functions) as a single sine function, and making sure that the shift angle, phi, is between negative pi and positive pi.
Solving quadratic trig equations where functions don't match: sin^2(t)=cos(t)
Просмотров 2978 лет назад
In this one I use the Pythagorean identity to rewrite sine squared in terms of cosine so that we can solve for t using the quadratic formula.
Solving a quadratic trig function with Cosecant: csc^2(t)=1
Просмотров 548 лет назад
In this one we use the fact that the reciprocal of the cosecant function is the sine function and then solve for solutions using what we know about the sine function and its solutions.
2sin^2x cosx = 1, solving a quadratic trig function
Просмотров 8 тыс.8 лет назад
In this problem we need to use the Pythagorean identity to rewrite sin^2(x) in terms of cosine and then factor and solve. There are three distinct families of curves. I find all solutions and then generate the solutions on the domain [0,2pi)
Rewrite 3sin(5x) + 4cos(5x) as Asin(Bx + C)
Просмотров 2,9 тыс.8 лет назад
In this example I do an example where C is in the first quadrant so the inverse tangent function describe C, and then I do an example that is almost exactly the same except because the coefficient 3 is negative C is in the second quadrant and the inverse tangent needs to be adjusted to be in the correct quadrant.
Rewrite As A Single Sine Function
Просмотров 6 тыс.8 лет назад
In this problem I use the sum identity for the sine function to rewrite the sum of a cosine function and a sine function as a single sine function.
Solveing an equation with Tangent squared.
Просмотров 968 лет назад
I go through the entire process needed to evaluate the function 1-2tan(x)=tan^2(x). I use a substitution, the quadratic equation, find all equations using a plus pi*k, and then find the solutions on [0,2pi).
Sum and Difference Identities Proofs - p2
Просмотров 3148 лет назад
This video continues on the justify the three other sine and cosine sum and difference identities
Sum and Difference Identity Proof Part 1
Просмотров 7 тыс.8 лет назад
Here I motivate the need for and then prove the difference identity for the cosine function: cos(A-B) = cos(A)cos(B) sin(A)sin(B). I use solving for an exact solution of cos(15degrees) to do this.
2cos3x=1
Просмотров 7 тыс.8 лет назад
Solving 2cos(3x) = 1 on the domain x = [0,pi). This will give a graphical reasoning behind the algebra as well as the algebra needed to solve for all solutions on the entire reals and then the specific solutions asked for in the problem.
Finding the sides and area of a right triangle
Просмотров 8910 лет назад
We are given an angle and the side adjacent and are asked to solve for the side opposite and the hypotenuse using exact values.
Calculate Volume of a solid given base and cross sectional
Просмотров 1,9 тыс.12 лет назад
Calculate Volume of a solid given base and cross sectional
Integration using u-substitution with additional steps
Просмотров 11512 лет назад
Integration using u-substitution with additional steps
Right Hand Approximation of Area under curve
Просмотров 77212 лет назад
Right Hand Approximation of Area under curve
Estimate area under the curve using a graph
Просмотров 6 тыс.12 лет назад
Estimate area under the curve using a graph
Section 5.1 #33 evaluating summations
Просмотров 49412 лет назад
Section 5.1 #33 evaluating summations
Quiz 3, prob 3: an example- limits resulting in oo-oo
Просмотров 5012 лет назад
Quiz 3, prob 3: an example- limits resulting in oo-oo
I gained a lot
And their was a mistake in your calculation. U wrote -27+44-18 instead of -27+44-28. Am sorry that I drop this in comment section instead of private message. Thanks ❤
But the answer i got is -11/√41.
Awesome
How about if u cross product axn
why do they have to on parallel planes?
The answer you got from projecting is a vector, isnt it so that you have to |d|= d * d and then find out the distance? so confused teachers do different
I think it'd be great if you could show why the magnitude of the projection of a onto n is d. Unlike in the case with parallel lines where the distance between the two lines does not change, it's not immediately obvious that in the scenario of skew lines, ||proj_n(a)|| is still d.
how do you know that point (6,3,0) lies exactly at the foot of normal which intersects both the lines??
ur account on insta
thank you so much!
What software do you use for the presentation? It’s nice and clear. Thank you.
I find a mistake at last step 18 should be 28 and need absolute value
Hello MathBySarah, I am thankful for your video. Thank you.
great explanation
Thank you
Lol who else came after Manoj Chauhan Sir's post
Lol my teacher recommended me this video.😅😅:)
Malik ki avaj badli badli si lag rhi hai🤣🤣
Saved me last minute thanks
I am here 😁
Thank u . Well explained 😃😍
THANKS !
Really poor handwriting.
Allah bless you ☺️
| Vr X Vp| , that is modulus of the cross product of the two vectors Vr and Vp itself will give the shortest distance.what is the purpose of projecting the distance vector on to the cross product.please clarify
once the two skew lines are contained in parallel planes, then they become PARALLEL.The explanation gets flawed there itself
@@MathBySarah But one can draw lines on the walls and floor of a room that are skew and those planes (wall, floor) intersect.
good
Very helpful you're a lifesaver
How did you know that x not for p(s) is the point of which a normal vector of the plane p lies on intersects line r(t)?
I don't know whether your doubt is solved or not but i had a same doubt !!!
if you try to calculate distance by having everything as variables at end you will see whether the fixed point is at the foot of perpendicular or not the distance comes to be constant.
that is same in both case , but the case with the fixed point here (6,3,0) at the foot of perpendicular is easy to visualise though it is not correct to assume it as assumed in the video !! (still answere doesn't change with or without the assumption )
To me, this was an unhelpful explanation. There is a much much much easier way to going about this. I've even attached my work so if you were confused by this answer hopefully youll understand mine. imgur.com/apn1d0L
I see how you would think that this was not what you wanted if you just wanted to simply find a solution to the problem and move one. The purpose of this question was to help my students at the time do problems that were far more complicated than this one and to understand the solution both graphically with the function, and how to use the unit circle to help find the two cosine solutions. You are absolutely right in that there is a much simpler way just to get the answer and move on. We both had different motivations for this video.
Thankyou
8:41 O_o
Awesome..
why N and vecA start at (6,3,0) thats not true!!!
Line a goes through the point (6,3,0) A vector valued function does is a collection of vectors whose tail is at the origin and whose head is a point on the line. That being said am not sure what you think is wrong. If you give me a time in the video I can take a look and explain further. I don't know how else to respond to this comment.
@@MathBySarah thanks so much .will get back to you 🙏
thanks for this! so clarified
Y u stop teaching.?
I am switching careers. I have graded enough homework sets and exams to fill a lifetime, and being a college instructor does not pay enough for me to send my own kids to college so I need to be in a career that will pay a little more than just above the poverty line. I enjoy explaining stuff to my friends and their children, so if you need something just ask, and I might have time to make more videos.
@@MathBySarah You are just awesome CUZ this video clarified a big doubt I had. Hope everything is fine :)
Niece
thanks so much for this video!!!!!!!!!!!!!!!!!!!!!!!! This is an amazing explanation!! love it!!!!!!!!!!!!!!!! definitely sharing this link
Thanks 💜
Gracias 😁
How agl qor=a-b
how would you work out this problem if both both sin and cos were squared. 2sin^2(x)cos^2(x)
Jose V, if it is equal to 1 I would set it equal to zero and factor into (sqrt(2)sin(x)cos(x) - 1)(sqrt(2)sin(x)cos(x) + 1)=0. And then each factor could be set to zero. And you can use the double angle identity to convert the sin(x)cos(x) into something easier to work with.
NICE EXPLANATION.
It helped me a lot. Thanks
Don't know whether you still read comments, but I wanted to let you know that I appreciate this video!
best video ever..thank you so much love from suriname
English ke chodal hawe ka
I think you made a mistake at 8:34. When doing the dot product of vectors n and a, you multiplied 7 by -4 for the J component and got -18 when it should've been -28.
Thank you Teacher Verry Useful Information ...
Pranth indaa
NOICE!