Answer:
√15
Step-by-step explanation:
Because x is an altitude, the largest triangle is similar to both the triangle on the left half and the triangle on the right half.
The ratio of 3 to x is equal to the ratio of x to 5 (because the triangles are similar, as stated earlier)
You write the following equation to represent it:
[tex]\frac{3}{x}=\frac{x}{5}[/tex], which (when the denominators are multiplied) results in:
[tex]15 = x^{2}[/tex]
Which makes x = √15
