causingaruckus,eh?
Find the norm of vector r prime of t when r(t) = t^2i + 2sintj + 2costk



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modphysnoob
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r'(t)=?
r(t) is given

modphysnoob
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so start with taking derivative

modphysnoob
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then square each component , add them

modphysnoob
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take square root

causingaruckus,eh?
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\[\sqrt(4t^2 + 4\cos^2t + 4\sin^2t)\]

causingaruckus,eh?
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What's the trig identity for cos and sin?

modphysnoob
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cos^2 t + sin^2 t =1

causingaruckus,eh?
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so does the second half of that just become 8?

modphysnoob
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4( 1)=4

causingaruckus,eh?
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Can you explain? I can never follow this one...

modphysnoob
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cos(t)^2+sin(t)^2=1
4(cos(t)^2+sin(t)^2)=4

causingaruckus,eh?
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Ohhhh.... Is that technically combining like terms?

modphysnoob
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I guess


modphysnoob
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no problem