pardon my repost..

1)  If you want to switch from radians to degrees, the relationship between the two is:

           2·pi (radians)  =  360 (degrees)     or     pi (radians)  =  180 (degrees)

 

    So, if you have  pi/6  radians and you want to switch it into degrees, replace the "pi" 

          with  "180^o     --->     this means that  pi / 6  becomes  180^o / 6  or  30^o

 

    To find  sin( pi / 6 ),  you can find  sin( 30^o  ).

 

2)  If triangle(ABC) has  AB = 25,  BC = 25,  and  AC = 40, then it must be an isosceles triangle.

     Draw the perpendicular from B down to side AC; call the point where they intersect X.

     To find  sin(ACB)  look at triangle(XCB):

     XC = 20  and  BC = 25.

     Using the Pythagorean Theorem to find BX:  BX² + XC²  =  BC².

          --->     BX² + 20²  =  25²     --->     BX² + 400  =  625     --->     BX²  =  225

          --->     BX  =  15

      sin(ACB)  =  opp / hyp  =  15/25