Question

How do you find all solutions if 0 ≤ θ < 2π for `sec 3x = −1`?

Answer 1

Solutions are `x=60^0,180^0,300^0`

Explanation:

`sec3x=-1 or 1/(cos3x)=-1 or cos 3x = -1; cos 180= -1 :. 3x=180 :.x=60^0`
for `0<=x<=360 or 0<=3x<=1080:. cos(180+360)= -1 :. 3x=540 or x=180^0 ; cos(540+360)= -1 :.3x=900 or x=300^0`So solutions are `x=60^0,180^0,300^0`[Ans]