What isn't the exact value for Sin (1305) degrees?

1305 is a measurement larger than 360, so keep subtracting 360 till you get a number smaller than 360, or divide by 360 to find the remainder

the number is 225

225 degree on a unit circle is in the 3rd quadrant, with the terminal line forming a 45 degree angle with the negative x axis. the y value is - √2/2, the hypotenuse is 1, so sin1305 = (-√2) / 2