The figure above will make sin and cos angle learning much easy. Asign degree values to your fingure as shown in figure. Always keep sqrt(_)/2 as default.
Here filling up sqrt(__) will give the anwer you are looking for.
For example, suppose you want sin30. Take your hand and asign values as shown in figure. Turn down the fingure with 30 deg assigned to it. Now count the fingures in the direction shown in figure. Here we get answer 1. Put 1 under squareroot. Now we get sqrt(1)/2=1/2. This is the answer for sin30.
Look at another example, cos60. Now turn down the fingure having 60deg assigened to it. Count remaining fingures in the given direction as in figure. You get 1 again. Substituting in default we get sqrt(1)/2 = 1/2 thus cos60 = 1/2.
Thus you dont have to memmorise the results of this values. Keep in mind only the angles 0, 30, 45, 60, 90 and thier multiples van be found in this manner. Hope you learned the tricks. Make trogonometry fun. Have a nice day. :-)