consider the function:

f(x)=3sin(2(x-30))-1
determine the first three x-intercepts to the right of the origin, rounded to the nearest tenth of a degree.

1 answer

That's better. For f(x) = 0, you need

sin(2x-60) = 1/3

Let sinθ = 1/3, so θ = 19.4°

2x - 60 = 19.4°
2x = 60 + 19.4°
x = 30 + 9.7°

Figuring that sin is positive in 1st and 2nd quadrants,

x = 180n + 120 - 9.7 = 180n + 110.3
for any integer n