Area of polar curve

  • Thread starter schaefer
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Main Question or Discussion Point

I've got a test tomorrow and I can't figure this one out:

r[tex]^{2}[/tex] = 9cos(5[tex]\vartheta[/tex])

I picked the inteval from 0 to [tex]\pi[/tex]/2 and I keep getting 18/5 but the back of the book says the answer is 18. I think something is wrong with my interval. Help Please!
 

Answers and Replies

  • #2
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when the angle changed from 0 to pi/2 ,you DON'T get the whole curve!
Try drawing out the curve.Note, cos(5*angle) must be > 0 to give a real point on the curve.

when angle=0, r=3
when angle=18 degree, r=0


hope this is helpful
 

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