Question

p2=a2cos2x + b2sin2x prove that p+d2p/dx2 =a2b2/p3

Answer 1

if p2=a2cos2θ+b2sin2θp2=a2cos2⁡θ+b2sin2⁡θ, show that p+p′′=a2b2/p3

2pp′=(b2−a2)sin2θ2pp′=(b2−a2)sin⁡2θ

p′2+pp′′=(b2−a2)cos2θ