Trigonometry: Compound angles: cos(A-B)=cosAcosB+sinAsinB

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  • Опубликовано: 20 сен 2024
  • This video proves cos(A-B)=cosAcosB+sinAsinB, from first principles.

Комментарии • 14

  • @karankanwar5498
    @karankanwar5498 6 лет назад +17

    i love it when my teacher understands maths instead of blindly memorising stuff.dats why i love this video cuz he does it in logical way with deep understanding.

  • @mariyah1608
    @mariyah1608 4 года назад +5

    Thank the lord someone made a video on COS compound angle because all the other ones online were for tan and sin, took me ages to find this

    • @WrightMaths
      @WrightMaths  4 года назад

      Glad to hear, it was one of my first videos to be uploaded...thanks.

  • @glennrickelton4093
    @glennrickelton4093 6 лет назад +4

    The best example of the proof of cos a - b using the distance formula I have seen because you don't just plot the points but show the triangles which give us those points. This visually shows sine a - sine b / cos b - cos a (in your example) works. Because when proving cos a + b by distance formula the points for b are usually moved into the fourth quadrant on the unit circle to make the sine negative, would it be impossible to do a similar video fo the proof of cos a + b showing the triangles and the distance formula?

  • @aditanjaria
    @aditanjaria 4 года назад +3

    Superb!! Great job!!!

  • @sony5492
    @sony5492 7 лет назад +5

    Very clear!Thank you

  • @stellafang4637
    @stellafang4637 7 лет назад +4

    THANKS FOR YOUR VIDEO

  • @kalyansundaram3500
    @kalyansundaram3500 6 лет назад +2

    Fantastic

  • @dihanfernando4710
    @dihanfernando4710 4 года назад +1

    Thank you very much

  • @rositasidauruk2264
    @rositasidauruk2264 4 года назад +1

    Can someone tell me why radi "1"?

    • @WrightMaths
      @WrightMaths  4 года назад +1

      Hi there, it's because the UNIT circle is where the definitions of sine and cosine originate from...