in f(x)=8+11 cos π/7 (x-2). find the first 3 positive values of x for whitch y=0

Answer 1

8 + 11cos[π/7(x - 2)] = 0

cos[π/7(x - 2)] = - 8/11

π/7 (x - 2) = cos^-1(-8/11) (This gives the first solution between 0 and 2π. To find the next solution, subtract

cos^-1(-8/11) from 2π. To find the 3rd, add 2π to cos^-1(-8/11).

Set π/7(x - 2) to each of those values and solve for x. Because the period of this cosine function is 14, the 3rd solution should be 14 greater than the first.