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Answer:
Number 4: Using Pythagoras Theorem,
[tex]\sqrt{30^2+40^2} =50[/tex]
Number 5:
[tex]\sqrt{41^2-40^2}=9[/tex]
3:
[tex]\sqrt{11^2+60^2} =61[/tex] It is a right triangle
4:
[tex]\sqrt{9^2+37^2} =38.09[/tex] Not a right triangle
For the last one:
[tex]\sqrt{(\sqrt{20^2+6^2})^2+6^2} =2\sqrt{118}[/tex]
Rounded down (because the answer needs to be a whole number) is 21