
#1
Feb1812, 12:05 AM

P: 33

all of my work so far is in the picture. i'm stuck on what i should do next.




#2
Feb1812, 05:06 AM

P: 615

your handwriting is incredibly neat, good show!




#3
Feb1812, 05:54 AM

Math
Emeritus
Sci Advisor
Thanks
PF Gold
P: 38,898

You are making the substitution [itex]x= a sin\theta[/itex] but then your integral has both x and [itex]\theta[/itex]. That's not right.
However, I would advise using the parametric equations [itex]x= a sin(\theta)[/itex], [itex]y= b cos(\theta)[/itex] rather than that complicated equation. 



#4
Feb1912, 04:48 PM

P: 33

circumference of an ellipse 



#5
Feb1912, 04:48 PM

P: 33





#6
Feb1912, 05:18 PM

Sci Advisor
HW Helper
Thanks
P: 25,174





#7
Feb2112, 05:30 PM

P: 33





#8
Feb2112, 05:36 PM

Sci Advisor
HW Helper
Thanks
P: 25,174





#9
Feb2112, 06:07 PM

P: 33

i completely reworked it, and it looks so much better now! lol.
now i have integral from 0 to a of sqrt(1 (b^2/a^2)cos(θ)) 



#10
Feb2112, 06:10 PM

Sci Advisor
HW Helper
Thanks
P: 25,174





#11
Feb2112, 06:14 PM

P: 33

right. k = 1(b^2/a^2). did i cancel sin^2(θ) instead of cos(θ)?




#12
Feb2112, 06:23 PM

Sci Advisor
HW Helper
Thanks
P: 25,174





#13
Feb2112, 07:00 PM

P: 33

sorry i'm a lot confused! 



#14
Feb2112, 09:37 PM

Sci Advisor
HW Helper
Thanks
P: 25,174





#15
Feb2112, 10:24 PM

P: 33

but if k = 1  (b^2/a^2) and under the radical says 1ksin^2(θ), shouldn't the end result under the radical, when expanded, be 1  (sin(θ))^2 (b^2/a^2)(sin(θ))^2?
and where does the 4 outside the integral come from? 



#16
Feb2112, 10:29 PM

Sci Advisor
HW Helper
Thanks
P: 25,174




Register to reply 
Related Discussions  
Spot the error! (circumference of ellipse)  General Math  2  
Equation of the circumference of an ellipse parametric equations  Calculus & Beyond Homework  9  
Circumference of an ellipse  Calculus & Beyond Homework  7  
Circumference of an Ellipse  Introductory Physics Homework  2  
circumference of an ellipse  General Math  1 