Another one!
I don´t get how to solve it please explain

Answer:
B. 16.9
Step-by-step explanation:
Reverse Pythagoreans theorem C^2 - B^2 = A^2 so
7^2 - 5^2 = c^2 and it comes out to
49-25 = 24 the square root of that is 4.9 (rounded)
But we are lookign for the perimeter so
4.9 + 7 + 5 = 16.9