pythagorean theorem
for a right triangle with legs (2 sides next to the the right angle) length a and b, and hyptonuse (longest side oposite right angle) is c
[tex]a^2+b^2=c^2[/tex]
we can see that the legs are 3cm and 7cm
so a=3 and b=7 (you can do a=7 and b=3 but it doesn't matter)
[tex]a^2+b^2=c^2[/tex]
[tex]3^2+7^2=c^2[/tex]
[tex]9+49=c^2[/tex]
[tex]58=c^2[/tex]
sqrare root both sides
[tex]\sqrt{58}=c[/tex]
[tex]c=\sqrt{58}[/tex]
answer is 4th option
