Answer:
48.2 cm
Explanation:
The bottom side of the large triangle has length 78 cm.
The bottom side of the right triangle has length 78 cm/2 = 39 cm.
Now we use the Pythagorean theorem to find the vertical side, the spine.
39² + s² = 62²
s² = 3844 - 1521
s² = 2323
s = 48.2
Answer: 48.2 cm