Add the whole numbers since they all have the square root of 6: 4+2-1=5. The answer is 5squre root of 6 or D :)
16² = 18² + 19² - 2(18)(19)cos(z)
256 = 324 + 361 - (684)cos(z)
256 = 685 - (684)cos(z)
-429 = -684cos(z)
cos(z) = -429/-684
z = cos⁻¹ (0.627)
z = cos⁻¹ (cos 51) [ Cos 51 = 0.627 ]
z = 51
In short, Your Answer would be: 51
Hope this helps!
