Answer:
when n=0, x=18°
when n=1, x= 90°
when n=2 x=18+72*2=162°
when n=3, x=18+72*3=234°
when n=4, x=18+72*4=306°
or
x= 18 + 72n, when n={0,1,2,3,4}
Explanation:
4sin(5x) =4
sin(5x) = 1
sin(α) = 1, when α=90° + 360n
5x = 90° +360n
x= 18 + 72n
when n=0, x=18°
when n=1, x= 90°
when n=2 x=18+72*2=162°
when n=3, x=18+72*3=234°
when n=4, x=18+72*4=306°
when n=5, x°=18+72*5 = 378°
General answer : x= 18 + 72n, when n={0,1,2,3,4}