Tolong bantu jawab kak,

[tex]a) \: \: {x}^{.} = \frac{1}{2} \cos(90) - \frac{ \sqrt{3} }{2} \sin(90) = - \frac{ \sqrt{3} }{2} \\ \: \: \: {y}^{.} = \frac{1}{2} \sin(90) + \frac{ \sqrt{3} }{2} \cos(90) = \frac{1}{2} [/tex]
[tex]b) \: {x}^{.} = - \frac{1}{2} - 0 = - \frac{1}{2} \\ {y}^{.} = 0 - \frac{ \sqrt{3} }{2} = - \frac{ \sqrt{3} }{2} [/tex]
c,d dengan cara yg sama