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# Parametric equation C4 watch

1. x= cos t

y= t(4-sint)

I got dt/dx = 1/ -sin t

dy/dt= 4-tcos t

dy/dx= 4-tcos t / -sin t

The answer is dy/ dx= t cost t - 4 cosec t +1
2. (Original post by APersonYo)
x= cos t

y= t(4-sint)

I got dt/dx = 1/ -sin t

dy/dt= 4-tcos t

dy/dx= 4-tcos t / -sin t

The answer is dy/ dx= t cost t - 4 cosec t +1
Your dy/dt is wrong. You didnt differentiate -tsint correctly.

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3. (Original post by APersonYo)
x= cos t

y= t(4-sint)

I got dt/dx = 1/ -sin t

dy/dt= 4-tcos t

dy/dx= 4-tcos t / -sin t

The answer is dy/ dx= t cost t - 4 cosec t +1
Use product rule for differentiating -tsint

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Updated: January 25, 2017
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