the measure of b is?

Answer:
b=21
Step-by-step explanation:
For this problem we need to use Pythagorean theorem (a^2+b^2=c^2):
20^2+b^2=29^2
Simplify the squares:
400+b^2=841
Subtract 400 from both sides:
b^2=441
Take the square root of both sides:
b=21
HTH :)