Answer:
12.69
Step-by-step explanation:
Use pythagorus theorem which says a^2+b^2=c^2
where a^2 and b^2 are the legs of the triangle and c^2 is the hypothenuse
(Plug into the equation)
1^2+b^2=13^2
(solve the 1^2 and 13^2)
1+b^2=169
(Substract 1 from both sides)
√b^2=√168
(Finally take the square root of 168 *this is very important*)
b=12.96
Round the answer.