Respuesta :

Answer: 60

Step-by-step explanation:

You have to use Pythagorean Theorem because the other side is not listed of the triangle

Pythagorean Theorem: a² + b² = c²

a²  + 20²  = 25²

a²  + 400 = 625

625-400 = a²

a²  = 225

Find the square root of 225 to find the missing length

[tex]\sqrt{225}[/tex] = 15 (this is the missing length for QS

To find the perimeter, add all the sides...

15 + 20 +25 = 60