tentukan himpunan penyelesaian dari cos 5x=1/2√2 untuk90° <×<=180°

cos 5x=1/2√2
cos 5x=cos 45°
x=(+_ a+k.360°)/5
u/k=0 x=(45°+(0)360°)/5=9°
x=(-45°+(0)360°)/5=-9°
u/k=1 x=(45°+(1)360°)/5=81°
x=(-45°+(1)(360°)/5=63°
u/k=2 x=(45°+(2)360°)/5=153°
x=(-45°+(2)360°/5=135°
hp={9°,63°,81°,135°,153°}
maaf klo ad yg slh