sin 3 x = sin ( 3 x + 2 π ) = sin [ 3 ( x + 2 π/ 3 ) ] = sin 3 x
This means "after the arc rotating three time of ( x + ( 2 π /3 ) ) , sin 3x comes back to its initial value"
So, the period of sin 3x is 2 π /3 .
Multiples of 15 are: 15,30,45,60,75,90,105,120,135,150,165,180,195,210,225,240,255,270,285,300,315,330,345,360,375,390,405,420,435,450,465,480,495,510,525,540,555,570,585,600,615,630,645,660,675,690,705,720,735,
