I have a Casio fx-9750GII, how do i switch my radians to degress?

412 Page Manual in the Link. Use CRTL_F to find.

https://www.google.com/search?q=change+d%2Fdx+into+d%2Fdy+on+a+Casio+fx-9750GII

..

Normally 500 x 20% = 100

https://www.google.com/search?q=Casio+fx-9750GII+percentages

..

Your angle unit is set to radians, while on the other calculators it is in degrees. Change the angle unit to degrees.

The 9750GII doesn't have symbolic capabilities so it can't give you a symbolic answer for this. It can evaluate it numerically at any point.

The derivative of sin(cos(x) dx is cos(cos(x))-sin(x).

Is it possible to change d/dx into d/dy on a Casio fx-9750GII? If so, how?

Turn calculator ON
If you see no icons, press Menu
Press 3 (Graph) draw your function. (more on that later).
If the first line of the display show Graph Func : Y= you should be able to draw your function.
If it says anything else, press F3 TYPE to select the graph type and select functional by pressing F1 key Y=.
After the graph type is set to Y=, type the second member of your function y= f(x) on the first line. Make sure the = sign after Y1= remains highlighted after you move cursor. Otherwise select the function by pressing F1:SEL. Press F6 Draw.
Be careful with trigonometric functions. If angle unit is radian, set window Zoom to standard. If angle unit is degree, you must open the Window utility and set Xmin=-190, Xmax = 190 to see at least a period.

The tangent of 60 radians is about 0.32, while the tangent of 60 degrees is about 1.73. To change the angular mode, press SHIFT [SETUP], down-arrow to the "ANGLE" line and then press the function key corresponding to the desired mode.

If your angle unit is set to degrees and your window dimensions are the standard ones (-10, 10) for Xmin, Xmax , then you will not see much of the graph. In that case you should set Xmin=-180, Ymax=+180 and Ymin=-1.2 and Ymax=1.2

If the angle unit is set to radians, then the standard window dimensions will show the characteristic graph.
Thus, change the angle unit or change the windows dimensions.

I am sorry, but the Casio FX-9750GII does not manipulate radicals (roots). Maybe you mean fractions?

1. Turn calculator on.
2. If you see no icons, press the[ MENU] key
3. Highlight RUN/MAT and press [EXE]
4. Press [SHIFT][MENU] to access (SetUp)
5. Pressing the down Arrow 5 times move the highlighting to the line ANGLE.
6. At the bottom of the screen 3 Tabs appear.
7. Press [F1:Deg¸]
8. Press [EXIT] to return to Main Run/Mat screen.