second order derivative

p2=a2Cos2θ+b2Sin2θ
then prove that

p+d2p/dθ2=a2b2/p3

11 Answers

1357
Manish Shankar ·

abhishek the hint is simple

p2=a2+(b2-a2)sin2θ

Now try to prove...

3
Abhishek Majumdar ·

thnx for the hint....i will try now and let u khow if i still face any problem while solving the problem!

11
Joydoot ghatak ·

@ manish

i guess the hint doesn't help much.....

3
Abhishek Majumdar ·

i am getting stuck after reaching the following step

(dp/dθ)2+p(d2p/dθ2)=(b2-a2)SinθCosθ

can somebody plz help me out after having reached this step??

49
Subhomoy Bakshi ·

why do u go by this way? it is just a simple problem!!! [11]

on differentiating w.r.t. θ

we get 2pdpdθ=(b2-a2)2.sinθcosθ

so, dpdθ=(b2-a2)2.sinθcosθ2p

so from here we get d2pdθ2

and then addd p to it!![1][1]

1
Ricky ·

Subho , this is a pretty pretty lengthy process if you go by this way !!!!

39
Dr.House ·

gallardo suggest something simple if dats long :)

62
Lokesh Verma ·

yes even i cant think of something simpler!

3
Abhishek Majumdar ·

I am not able to solve the problem......
can somebody help me out???
plzz

1
Manmay kumar Mohanty ·

abhisek i thnk u made a typo in the question
that shuld have been p = a2cos2θ + b2sin2θ
not p2 = a2cos2θ + b2sin2θ

[7]

3
Abhishek Majumdar ·

no the question states

p2=a2cos2θ+b2sin2θ only!!!! :(

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