Respuesta :

Answer:

x ≈ 14.7

Step-by-step explanation:

use pythagorean therorem

a^2 + b^2 = c^2

c is hypotenuse and we know the hypotenuse is 21

a^2 + b^2 = c^2

x^2 + 15^2 = 21^2

x^2 + 225 = 441

x^2 = 216

x = √216

x ≈ 14.7