Answer:
20
Step-by-step explanation
use the formula a²+b²=c²
since a=21 and c=29 you need to solve for b
Put 21 in for a and 29 in for c
21²+b²=29²
21²=441
29²=841
so then the equation would be 441+b²=841
subtract both sides by 441
then you have b²=400
now just find the square root of 400
√b²=√400
b=20
