Hello!
You use the Pythagorean theorem for this
Pythagorean theorem is [tex] a^{2} + b^{2} = c^{2} [/tex]
C is the hypotenuse or the side across the right angle
A and B are the other two sides
Put in the values you know
[tex] 25^{2} + 30^{2} = c^{2} [/tex]
square the numbers
625 + 900 = [tex] c^{2} [/tex]
Combine like terms
1525 = [tex] c^{2} [/tex]
take the square root of 1525
You get the answer of 39.1
The answer is 39.1
Hope this helps!