The area of square $ABCD$ is $196 \text{cm}^2$. Point $E$ is inside the square, at the same distances from points $D$ and $C$, and such that $m \angle DEC = 150^{\circ}$. What is the perimeter of $\triangle ABE$ equal to? Prove your answer is correct.
1. **Determine the side length of the square \(ABCD\):**
   The area of the square \(ABCD\) is given as \(196 \text{cm}^2\). The side length \(s\) of the square can be found using the formula for the area of a square:
   \[
   s^2 = 196 \implies s = \sqrt{196} = 14 \text{cm}
   \]

2. **Identify the properties of point \(E\):**
   Point \(E\) is inside the square and equidistant from points \(D\) and \(C\). This implies that \(E\) lies on the perpendicular bisector of segment \(DC\). Since \(DC\) is a side of the square, the perpendicular bisector of \(DC\) is the vertical line passing through the midpoint of \(DC\).

3. **Analyze the angle condition:**
   Given that \(m \angle DEC = 150^\circ\), we need to consider the geometric implications. Since \(E\) is equidistant from \(D\) and \(C\), and the angle \(DEC\) is \(150^\circ\), we can infer that \(E\) forms an equilateral triangle with points \(D\) and \(C\).

4. **Construct an equilateral triangle:**
   Let \(E'\) be the point such that \(\triangle ABE'\) is equilateral. We need to show that \(E'\) satisfies the conditions of point \(E\).

5. **Verify the equilateral triangle condition:**
   If \(\triangle ABE'\) is equilateral, then each side of \(\triangle ABE'\) is equal to the side length of the square, which is \(14 \text{cm}\). This implies that \(AE' = BE' = AB = 14 \text{cm}\).

6. **Check the angle condition:**
   In an equilateral triangle, all angles are \(60^\circ\). Therefore, if \(\triangle ABE'\) is equilateral, then \(\angle ABE' = 60^\circ\). However, we need to check if \(\angle DEC = 150^\circ\) is satisfied.

7. **Reconstruct the point \(E\):**
   Since \(E\) is equidistant from \(D\) and \(C\) and \(\angle DEC = 150^\circ\), we can conclude that \(E\) must be the same point as \(E'\) in the equilateral triangle \(\triangle ABE'\).

8. **Calculate the perimeter of \(\triangle ABE\):**
   Since \(\triangle ABE\) is equilateral with each side equal to \(14 \text{cm}\), the perimeter of \(\triangle ABE\) is:
   \[
   \text{Perimeter of } \triangle ABE = 3 \times 14 = 42 \text{cm}
   \]

The final answer is \(\boxed{42 \text{cm}}\).