Question

If a=k sin M cos N,b=k sin M sin N and c =k cos M, prove that :a^2+b^2+c^2=k^2​

Answer 1

Answer:

a2−b2)sinθ+2abcosθ=a2+b2Leta=kcosϕ,b=ksinϕ,a 2+b2=k2,tanϕ=b/ak2(cos2ϕ−sin2ϕ)sinθ+2k2cosϕsin θ=k2cos2ϕsinϕ+sin2ϕcosθ=1sin(2ϕ+θ)=1θ=2π−2  ...