this concerns high school level math, and graphing trig functions

I’m stuck

you are given a graph of a cosine function, minimum point at (8 pi /3, -2), maximums at (2 pi/3, 4) and (14 pi /3, 4)

(basically looks like a “v” just right of the y axis)

the function is of the form

y = a cos(bx + c) + d

you are asked to find a, b, c, and d, and the smallest positive zero of the function

so I’ve found

a = 3

b = 1/2

c = -2 pi /3

d = 1

so the curve crosses the x axis somewhere between 4 pi/3 and 8 pi /3

how can I find that exact point?

thanks for reading:cool: