Answer:
[tex]x = \sqrt{143}[/tex]
Step-by-step explanation:
We know that all three triangles formed by dropping a right triangle's altitude (here labeled [tex]x[/tex]) are similar.
This means that the ratios of their side lengths are equal. We can use this property to solve for [tex]x[/tex]:
[tex]\dfrac{\text{short leg of small }\triangle }{\text{long leg of small }\triangle} = \dfrac{\text{short leg of medium }\triangle }{\text{long leg of medium }\triangle}[/tex]
↓ plugging in the given values
[tex]\dfrac{11}{x} = \dfrac{x}{13}[/tex]
↓ cross-multiplying
[tex]x^2 = 11 \cdot 13[/tex]
↓ taking the square root of both sides
[tex]\boxed{x = \sqrt{143}}[/tex]