∫∫∫√(x^2+y^2+z^2)dv
用球坐标
=∫∫∫ r*r²sinφ drdφdθ
=∫[0→2π]dθ∫[0→π] sinφdφ∫[0→R] r³ dr
=2π(-cosφ)∫[0→R] r³ dr |[0→π]
=4π∫[0→R] r³ dr
=πr^4 |[0→R]
=πR^4
∫∫∫√(x^2+y^2+z^2)dv
用球坐标
=∫∫∫ r*r²sinφ drdφdθ
=∫[0→2π]dθ∫[0→π] sinφdφ∫[0→R] r³ dr
=2π(-cosφ)∫[0→R] r³ dr |[0→π]
=4π∫[0→R] r³ dr
=πr^4 |[0→R]
=πR^4