Question

John is trying to determine the length of the staircase he will need for a deck that is 12 feet high he wants to start the stairs 21 feet from the deck

Answer 1

right triangle
legs are 21 and 12

a^2+b^2=c^2
12^2+21^2=c^2
144+441=c^2
585=c^2
sqrt both sides
5√65=c
aprox
24.1868=c

about 24.2 feet