Try this. Plot 4^2*cos(x)*sin(x)/(4*sqrt(6^2-(4^2/4*sin(x)^2)))+4/2*sin(x) with radians mode set and the x range set at xmin=0 xmax=2*pi.

My result shows a maximum at x=1.27298225215758 radians. Now change the mode to degrees and the the xmax to 360.My result shows a maximum at

x=60.8717519044877 degrees.If I convert 1.27298225215758 radians to degrees I get 72.9365104436877 degrees, considerably different than 60.8717519044877 degrees. using the online function calculator

1.27714985743 radians is the correct maximum

which converts to 73.17529661 degrees. This result seems correct to me. Is there any way to get the correct results using graphcalc??