Answer: x=5
Explanation:
If you broke your triangle in half, it would create a right triangle, with:
long leg = 4
hypotenuse = x
short leg = 3 >it's half of the full base of the main triangle
You can use pythagorean theorem to solve:
c²=a²+b² >substitute
x²= = 4²+3² >simplify
x² = 16 + 9
x² = 25 >take square root of both sides
x = 5