Because this triangle is a right traingle and has one angel that is 45 degrees, the third angle must be 45 degrees to because 90+45+45=180. With that, km must be the same length as lm. we know lm is 5 so km is 5 too. No we can plug this into the Pythagorean Theorem too get
5^2+5^2=c^2
25+25=c^2
50=c^2
√50=√c^2
√25*2=c
5√2=c
Thats your answer to the length of lk.
