Plz,... I want to know about the cos tan sin vaues.

  (2cos 40 - cos 20)/sin 20

$$[2cos^220-2sin^220-cos20]/sin20\\

=[2-2sin^220-2sin^20-cos20]/sin20\\

=[2-4sin^220-cos20]/sin20\\

=2cosec20-4sin20-cot20\\

=\mbox{I am just playing here, Aziz is right, there is not much you can do with this}$$

You can enter it into the web2 calc like this.  

 (2*cos(40)-cos(20))/sin(20)

=$${\frac{\left({\mathtt{2}}{\mathtt{\,\times\,}}\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{cos}}{\left({\mathtt{40}}^\circ\right)}{\mathtt{\,-\,}}\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{cos}}{\left({\mathtt{20}}^\circ\right)}\right)}{\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{sin}}{\left({\mathtt{20}}^\circ\right)}}} = {\mathtt{1.732\: \!050\: \!807\: \!567\: \!060\: \!3}}$$

Okay the answers are different.  

Aziz has assumed radians, which is a correct assumption because it you do not specifiy the units then by default it is radians.

I have used degrees because I am used to school students and I assume that is what you actually wanted.

So 2 different interpretations (both reasonable) have produced 2 different answers.

Since none of the numbers (40, 20, & 20) are in degree form, we use the radian or "rad" function on the calculator. The expression becomes ((2*cos(40) - cos(20)) / sin(20). Remember, parentheses are very important! I assumed the 2 will only be multiplied with the cos(40) and that it does not read 2(cos(40) - cos(20)) since that would yield a different answer. After getting the values for cos(40), cos(20), and sin(20) and replacing them with decimals, we get:

[(2*(-0.6669)) - (0.40808)] / (0.9129) = -1.908 as the final answer.

*Make sure you use the "rad" function. Usually, degree or "deg" is the default form, so you will have to switch from "Deg" to "Rad" on the calculator on this website, for example.*