Respuesta :

Answer:

15

Step-by-step explanation:

(whole secant) x (external part) = (tangent)^2

(5+x) * 5 = 10^2

Distribute

25 +5x = 100

Subtract 25 from each side

25-25 +5x = 100-25

5x= 75

Divide by 5

5x/5 = 75/5

x = 15