Respuesta :
These relations all follow from the identity,
sin(x - y) = sin(x) cos(y) - cos(x) sin(y)
Notice that 160° = 180° - 20°, so if x = 180° and y = 20° above, we get
sin(160°) = sin(180°) cos(20°) - cos(180°) sin(20°)
We know sin(180°) = 0 and cos(180°) = -1, so we end up with
sin(160°) = sin(20°)
For the other, notice that 200° = 360° - 160°, and 340° = 360° - 20°.
Answer:
Step-by-step explanation:
sin 20 is the same as sin 60 because 180-60=20. sin 20 is the same as -sin200 because 200-180=20
sin 340 is the same as sin 20 because 360-340=20. So all four of these connect and they all equal 20. Also, they all equal .3420 (rounded)