Hello Marcela,
Any sine function has this general equation: y = A sin (Bx + C) + D where:
A = amplitude
B = 2pi/Period
C = phase shift
D = midline
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You're told the sine function has:
- an amplitude of 3 so A = 3
- a midline of 5 so D = 5
- a period of 7π/3 so B = 2π/(7π/3) = 2π * 3/7π = 6π/7π = 6/7
- no mention of phase shift so C = 0
Putting it all together, your sine function will be y = 3 sin (6x/7) + 5