sin(2 arccos(2/25))=
arccos (2/25)=cos⁻¹ (2/25)=85.41143....
2(arc cos (2/25)=2(85.41143...)=170.82286....
sin(2arccos (2/25))=sin 170.82286....=0.159487....≈0.16
Answer: the exact value of sin(2 arccos(2/25) is sin (2 cos⁻¹(2/25)) and it is approximately 0.16
