Answer:
D. x=4
Step-by-step explanation:
We can solve this with the Pythagorean Theorem for the right triangle that we can see (which is half of the triangle).
The bottom length is 3 and the hypotenuse is 5.
The Pythagorean Theorem is a²+b²=c².
We can plug this in:
3²+x²=5²
9+x²=25
x²=16
x=4
