sin(1755o) = -0.707106781187 via calculator
1755/360 = 4 and a bit
so it is 4 revolutions plus a partial revolution
Sin 1755 = sin 315
315 degrees is in the 4th quadrant where sin is always negative.
sin 315 = -sin 45 degrees
Draw a right angled, isosceles triangle with the legs being 1 unit in length.
the angles are 90, 45 and 45 degrees
Use pythagoras's Theorum to find the hypotenuse.
From that you can work out what sin450 is.