<span>Standard deviation is the square root of variance. Variance is always a non-negative number, since you can't take the square root of a negative number. So neither can be negative </span>
In brief, apply the pythagorean theorem to show that the distance between the point and the origin is .
Step-by-step explanation:
The pythagorean theorem can give the distance between two points on a plane if their coordinates are known.
A point is on a circle if its distance from the center of the circle is the same as the radius of the circle.
On a cartesian plane, the unit circle is a circle
centered at the origin
with radius .
Therefore, to show that the point is on the unit circle, show that the distance between and equals to .
What's the distance between and ?
.
By the pythagorean theorem, the distance between and the center of the unit circle, , is the same as the radius of the unit circle, . As a result, the point is on the unit circle.