Example 4 if cos^-1(x)+cos^-1(y)+cos^-1(z)=π show that x^2+y^2+z^2+2xyz=1

Example 4 if cos^-1(x)+cos^-1(y)+cos^-1(z)=π show that x^2+y^2+z^2+2xyz=1

Namaskar this video If cos^–1x + cos^–1y + cos^–1z = π prove that x^2 + y^2 + z^2 + 2xyz = 1 Prove that cos-1 x+ cos-1y=cos-1[xy-√(1-x^2)√(1-y^2)] ___ thanks watch this video have a nice day