Respuesta :

I might just give two of them.
28. y=45°, 
13x13=169
169/2=84.5
√84.5=x
x=2√21+√2/2
31. (5√2)²=50
50/2=25
x=√25=5
(5√2)²+(5√2)²=100
y=√100=10
Those are your answer.