please help me on this thing

Answer:
68 cm
Step-by-step explanation:
Use the following formula (Pythagorean Theorem) to solve for c:
[tex]c^{2}= \sqrt{(a^{2}) - (b^{2})[/tex]
Substitute values:
[tex]c^{2}= \sqrt{(77^{2}) - (36^{2})[/tex]
Simplify:
[tex]c^{2}= \sqrt{(5,929) - (1,296)}[/tex]
[tex]c^{2}= \sqrt{4633}[/tex]
c ≈ 68 (rounded from 68.07)