If these two shapes are similar, what is the measure of the missing length a?

the answer is b: 18

step-by-step explanation:

use the pythagorean theorem to .

a^2+b^2=c^2

plug 18 for "r"

the 2 legs are 18 and 24

18^2+24^2=c^2

324+576=c^2

900=c^2

c=30

30-12=18

18 is the radius

: )

1,2,4,5,10,11,20,22,44,55,110,220

it would be r^2 - 2rs +s^2

assuming   you mean to square it

i definitely need a figure to answer you question correctly! : (