Answer:
1260°
Explanation:
To start this with, we find the total number of sides that the said polygon has. And this can be done by saying
Since each interior angle equals 140, then the formula suffices.
[(n-2) * 180] / n = 140
On solving this, we have
n-2 * 180 = 140n
180n - 360 = 140n
180n - 140n = 360
40n = 360
n = 360 / 40
n = 9
This means the number of sides in the polygon is 9
Therefore, the sum of all interior angle is
n-2 * 180 =
9-2 * 180 =
7 * 180 = 1260°
Thus, the total sum of all interior angles of the polygon is 1260°
