Answer: 20.8
Explanation:
Since it is an equilateral triangle, we know the bottom is also 24. We also know that line E is bisecting the base. So using the smaller right triangle we know that the hypotenuse is 24 and one leg is 12. So use the Pythagorean theorem.
![a^(2) +b^(2) =c^(2) \\12^(2) +b^(2) =24^(2) \\144+b^(2) =576\\b^(2) = 432\\b= 20.8](https://img.qammunity.org/2022/formulas/mathematics/high-school/o83z49h8fm8x4g2f29h1usvxwndzo63iq3.png)