Answer:
x = [tex]\sqrt{87}[/tex]
Step-by-step explanation:
if you draw a perpendicular segment from the vertex between sides 5 and 16 to the opposite side then you have a right triangle and can use the Pythagorean Theorem, a² + b² = c²
a = x
b = 13 (you get this from 18 - 5)
c = 16
x² + 13² = 16²
x² + 169 = 256
x² = 87
x = √87
