Answer:
28
Explanation:
Intersecting secant theorem:
If two secant segments drawn to a circle from an exterior point, then the product of measures of one secant segment and its external secant segment is equal to the product of the measures of the other secant segment and its external secant segment.
SO = 14 + 4 = 18 ; SR = 14
SU = 9 +z ; ST = 9
SO * SR = SU * ST
18 * 14 = (9 + z) *9
252= 9*9 + 9 *z {Distributive property}
252 = 81 + 9z
Subtract 81 from both sdies,
252 - 81 = 9z
171 = 9z
9z = 171
Divide both sides by 9,
z = 171 ÷ 9
z = 19
SU = 19 +z
= 19 + 9
= 28