Question

Plz find the value of x in this attachment

Answer 1

cos [ 2 cos^-1 √1 -x² ] = 1/9
cos [ cos ^-1 {2( 1- x²) -1 } ] = 1/9
2( 1- x² ) - 1 = 1/9
2 - 2x² - 1 = 1/9
2x² = 1 - 1/9
2x² = 8/9
x² = 4/9
x = 2/3