Answer:
n = 3
Explanation:
The terminal side of an angle fall along the positive portion of the y-axis,
If it can written in the form of (90°)a
Where a is any positive odd integer,
Here, the given angle is,
(870n)°,
For n = 3,
Our angle will be 2610°
Its terminal side fall along the positive portion of the y-axis,
If 2610° = (90°)a ⇒ a = 29 ( Positive odd integer )
Thus, for n = 3, the terminal side of the angle (870n)° falls along the positive portion of the y-axis,
For n = 4,
Our angle will be 3480°
Its terminal side fall along the positive portion of the y-axis,
If 3480° = (90°)a ⇒ a = 38.6667 ( Not possible )
Thus, for n = 4, the terminal side of the angle (870n)° does not fall along the positive portion of the y-axis
For n = 5,
Our angle will be 4350°
Its terminal side fall along the positive portion of the y-axis,
If 4350° = (90°)a ⇒ a = 48.333.. ( Not possible )
Thus, for n = 5, the terminal side of the angle (870n)° does not fall along the positive portion of the y-axis,
For n = 6,
Our angle will be 5220°
Its terminal side fall along the positive portion of the y-axis,
If 5220° = (90°)a ⇒ a = 58 ( Not possible )
Thus, for n = 6, the terminal side of the angle (870n)° does not fall along the positive portion of the y-axis.