To find the scale factor between two similar triangles, you can use the lengths of their corresponding sides. In this case, the hypotenuse of the first triangle is 12 cm and the hypotenuse of the second triangle is 48 cm.
The scale factor (k) can be calculated using the following formula:
\[ k = \frac{\text{length of hypotenuse of the larger triangle}}{\text{length of hypotenuse of the smaller triangle}} = \frac{48 \text{ cm}}{12 \text{ cm}} = 4 \]
Thus, the scale factor is 4. This means that the second triangle is 4 times larger than the first triangle.