Parametric Equations : Tangents and Normals : ExamSolutions

Tutorial on tangents and normals to parametric equations.

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[spag]

For anyone without annotations on, Stuart has included in an annotation that t=-2 was a mistake, at 7:08.

[rashmiii]

your explanations are very clear sir. thank you so much❤

[fahimal-huq]

Thanks a lot sir..Very clear explanation

[lazer]

at 5:20, what if in a question, both of the values satisfied the Y equation? which one would you use?

[salmaahmadkhan]

Hi Sir, I love your videos and soluitions as they are extremely helpful.question; why did you take t=-2 and not t=+2?

[fahadjhljh]

wouldn't (3t^2-1)/2t equation be the equation for the curve of x and y and the derivative of this equation will be the gradient for tangent? Please help. Thanks

[ExamSolutions_Maths]

Both of them I suppose but I am sure there will be some clause in the question to stop this from being the case.

[lungilentulie]

thank you so much sir your explanation help me a lot.

[michaelgich]

thank you very much sir, the video helped me a lot

[stripedbandit]

Hi if I can ask a question, why don’t u use y=mx + c when trying to find your tangent or normals? Why y2-y1=m(x2-x1)? Just wondering I never understood this thanks!

[ExamSolutions_Maths]

-16-66 = - 82. Sorry, but I think you will find that I am correct on this one.

[oatie]

How did you know that we should be using the x-coordinate 4 and x = t^2 to find t?

[ExamSolutions_Maths]

Look at Edexcel Jan 2009 Q7 last part. I have a video on the kind of thing yoou are asking. Hope it helps.

[Genji_Glove]

7:05, did you mean t=-2 at that point? Corrective annotation? :) Thanks for the vids!

[ExamSolutions_Maths]

Yes but as you said this would be very long winded.

[omnme]

THERE IS AN EASIER WAY TO SOLVE THIS (Just sayin')

x=t^2 and y=t^3-t

so y=(t^2)t-t therefore y=xt-t


sub. x & y

-6=4t-t which gives t=-2

eqn. of tangent is [y=-2x-2]

gradient of normal is -1/(gradient) i.e 0.5


eqn. of line is y=mx+c

sub. x, y & new gradient

you get y=0.5x-8 => eqn. of normal

Very simple :) correct me if i'm wrong, coz honestly i dnt know if i'm right

[HKqLimAxzU]

Was there any need to work out the y values?

[labibatahsin]

Wasn't the last part, eqn of normal supposed to be

[the_hasnat]

How many marks would a question like this be?

[kishanshrestha]

U hav a mistake on replacing the value of t .... U just kept the value of t as 2 where as it should b -2