Hey could I please get some help with my math?:) which of the following sets of numbers could be the side lengths of a triangle?

10, 10, and 30
4, 7, and 13
2, 3, and 4
9, 13, and 23

the answer is  20,21,29 because  

20 times 20 is 400

21 times 21 is 441

and 29 times 29 is 841

the formula to ge tthe answer is a^2 + b^2 = c^2

20^2 + 21^2= 29^2

then plug the rest in

400+441= 841

Step-by-step explanation:

can i get crown now?

the first 1 I'm pretty sure

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have a good rest of your day/afternoon :) ❤

idk

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the equation cos(35) =a/25 can be used to find the length of bc what is the length of bc? round to the nearest tenth

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