9514 1404 393
Answer:
x = 14.4
Explanation:
The product of segment lengths for each chord is the same.
8·36 = x·20
x = 8·36/20 . . . . divide by 20
x = 14.4
_____
Additional comment
There are a couple of relationships involving lengths of chords and secants. I consider each to be a specific case of the general rule that the product of segment lengths from the point of intersection to its two circle intercepts is the same for each chord/secant/tangent.
When the point of intersection is inside the circle, as here, the two lengths are those that extend either side of the point of intersection. When the point of intersection is outside the circle, then the segments of interest are the short one that intersects the circle at a near point, and the longer one that intersects the far side of the circle.
Yet another special case of the intersection point being outside is the case where the two intercepts are identical—the "secant" is a tangent. In that case, the tangent length is squared (multiplied by itself).
Personally, I find the general rule easier to remember than all of the special cases.