1.
x = 6 cos 150, y = 6 sin 150
x = -3√3, y = 3
since x² + y² = 6² , you can plug in the values for x and y and check that (-3√3)² + 3² = 36.
2.
a = 4 cos 300, b = 4 sin 300
a = 2, b = -2√3
since a² + b² = 4² , you can plug in the values for a and b and check that 2² + (-2√3)² = 16.