Grade 12 Trigonometry Lesson 8| Trig equations Involving double angles

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  • Опубликовано: 30 ноя 2024

Комментарии • 71

  • @mandlajonas8327
    @mandlajonas8327 2 года назад +86

    I'm getting a 100% for both math and physics this year. Remember my words .(thank you sir for your lessons)!!!

  • @KefilweChantel
    @KefilweChantel 9 месяцев назад +18

    Sir for sin,
    90- -30 is 120 not 110
    Hence it’s giving you the value of x as 110-2x k.360 instead of 33,3+ 120k.360 like the the cos one

  • @NontandoMbeje
    @NontandoMbeje 2 года назад +13

    I'm passing Maths because of you Mr ❤️ thank you so much

  • @Maroundy.19
    @Maroundy.19 Год назад +13

    I will succeed in maths and physics this year ❤🎉

  • @uhurulodge2989
    @uhurulodge2989 2 года назад +15

    Sir you made a mistake there at 90-(-30) you wrote 110 and it’s 120

  • @elvinmandikiyana8757
    @elvinmandikiyana8757 Год назад +11

    was it not supposed to be -4x = k360 - 90 which then gives x = 22.5 -k90 for the very first solution

  • @vusihadebe4972
    @vusihadebe4972 2 года назад +2

    You are really good sir on teaching this subject keep it this way 🤙

  • @saneleterence8297
    @saneleterence8297 2 года назад +7

    Afternoon sir , can you please also please do trigonometric equations using double and compound angles 😭🥺🤧. And sir thank you your lessons have helped me alot

    • @MlungisiNkosi
      @MlungisiNkosi  2 года назад +4

      You're most welcome. Please check in my earlier posts. Those lessons already exist.

  • @kamogelomodjadji4005
    @kamogelomodjadji4005 2 года назад +2

    Thank you sir Nkosi for the lessons they are helpful

  • @NontandoMbeje
    @NontandoMbeje 2 года назад +3

    Please Matrics let's try and watch these ads 😍 road to 150k subscribers

  • @estherondongo1744
    @estherondongo1744 28 дней назад +1

    Sir is this like genereal solutions?

  • @saraasare699
    @saraasare699 Год назад +1

    👏👏👏👏

  • @Aphiwerh23
    @Aphiwerh23 Год назад +1

    Good day sir, I'm curious for the last example why we would subtract 180 from sin whereas we didn't subtract 360 from cos?

  • @rachealnkosi8567
    @rachealnkosi8567 2 года назад +7

    Good day sir I don't understand how you got 110 instead of 120 on the last question?? Please help 🥺

    • @MlungisiNkosi
      @MlungisiNkosi  2 года назад +6

      Mkhulu Mlu made a biiiiggggg mistake. Askies MaNkosi

  • @dark8dy
    @dark8dy 2 года назад +3

    Good day Sir, Can you please explain to me example 2 and 3, on why you said cos is +/- . Why didn't you check where cos is positive or negative on the cartesian plane like you did using the sin?. ( not sure if you understand my question)🙃

    • @MlungisiNkosi
      @MlungisiNkosi  2 года назад +1

      Please start from the beginning of this series…

  • @shudumutepe4768
    @shudumutepe4768 2 года назад +2

    Do I still get it right if I changed sin to cos in the last example?

  • @trustlorrd
    @trustlorrd 2 года назад +2

    sir for the last example when you transposing 2x to the left, isn't supposed to be - 2x so that the final answer is - 3x?

  • @Nthangeni_funi
    @Nthangeni_funi 2 года назад +3

    Sir can I ask something..
    In example 2 we divided everything by -2 ...aren't we supposed to get -180 when we divide 360 by -2

    • @MlungisiNkosi
      @MlungisiNkosi  2 года назад +2

      That’s true! Did I make an error?

    • @flexace768
      @flexace768 2 года назад +4

      @@MlungisiNkosi yeah I also think so but nowa the problem is in a situation when u have
      90°-2x = X-10°
      The final answer won't b the same
      1. -3X = -100+360K 2. 100+360k=3X
      Which on should be a solution coz if I divide -3 on Solution 1 the answer -120K
      But if divide 3 on solution 2 the answer +120k

    • @MlungisiNkosi
      @MlungisiNkosi  2 года назад

      @@flexace768 remember k is an element of real numbers… Meaning, k can be equal to +/- values.

    • @flexace768
      @flexace768 2 года назад +1

      @@MlungisiNkosi so in that situation both answers are correct

    • @duckduckgooze302
      @duckduckgooze302 Год назад +1

      ​@MlungisiNkosi so that means we always leave our k positive since it's the element of integers, even if we divide it by a negative?

  • @gracemaria1696
    @gracemaria1696 2 года назад +1

    Hey sir I was just asking if you would do more examples wherein we have to factorise

    • @MlungisiNkosi
      @MlungisiNkosi  2 года назад

      That will not solve your problems. What you need to do now is try the examples yourself

    • @gracemaria1696
      @gracemaria1696 2 года назад +1

      @@MlungisiNkosi okay sir

  • @la_papillon
    @la_papillon Год назад +1

    Sir why is it that in example 2 when you took the 90 to the oppisite side the sign didn't change?

  • @NotAN00B
    @NotAN00B 2 года назад +2

    i know its been months since the upload but can someone help me with example 1:
    when the 90 was taken to the other side was it divided by negative1 just like -4x, if so then why not apply the same thing to the 360k on the other side

    • @MlungisiNkosi
      @MlungisiNkosi  2 года назад +1

      You don’t have to because k can be negative or positive 😊

    • @NotAN00B
      @NotAN00B 2 года назад +1

      @@MlungisiNkosi thank you sir

  • @thokozanitamela673
    @thokozanitamela673 2 года назад +4

    Mr Nkosi please do Probability on your next coming series,I'm really struggling with that one 🙏🙏

  • @sethembilemzolo7133
    @sethembilemzolo7133 2 года назад +1

    Thanks 🙏

  • @nivzy_m
    @nivzy_m 2 года назад +1

    even if K360 is negative you can put it as positive? sir, that's what I noticed but I'm not sure

  • @NonzwakaziNqashe
    @NonzwakaziNqashe 2 месяца назад +1

    6:39 sir are we not dividing 360K by negative 2 isn't it supposed to change sign?

    • @MlungisiNkosi
      @MlungisiNkosi  2 месяца назад +1

      You may but it’s not necessary since you substitute k with integers

  • @nkanyisoxulu6934
    @nkanyisoxulu6934 Год назад

    X=30+k120;k€z is correct?

  • @nkanyisoxulu6934
    @nkanyisoxulu6934 Год назад +1

    But the first i confused by (_) it like this x+20=_(110_2X)+K360 the firs thing i remove blacket with negative then i got different answer

  • @thabanggama
    @thabanggama 7 месяцев назад +1

    Hi Sir is there lesson 7 .I can't see it.

  • @michaelstyles8649
    @michaelstyles8649 Год назад +1

    Hi, sir. I couldn't help but notice that lesson 6 & 7 are missing from the catalog. 😭

  • @sunnyboymkhasibe9995
    @sunnyboymkhasibe9995 2 года назад

    Good evening Mr. Mlungisi, I would like to know if for some reason you took the x to the left side and it became negative, and the 90 also became negative, does it influence the positive of the +k360?

    • @MlungisiNkosi
      @MlungisiNkosi  2 года назад

      No it doesn’t… As long as the frequency stays the same

  • @nalediramogayane4840
    @nalediramogayane4840 2 года назад +1

    Hi sir, when we divide by the -2, doesn't it affect the k360?