Final answer:
When the width of a triangle is reduced to 4 cm, the height will be 1 cm.
Step-by-step explanation:
To determine the height of the triangle when the width is reduced to 4 cm, we can use the concept of similar triangles. Since the ratio of the widths is 12 cm to 4 cm, or 3 to 1, we can apply the same ratio to the heights. Therefore, the height will be 3 cm divided by 3, which equals 1 cm.
Learn more about relationship between the width and height of a triangle