Given m<A and a: find b o.o?

I'm new to trig and I'm trying to figure out a problem but I'm stuck on the last step.
I know that A=45 degrees and a= 21
so I did the problems to this step:

b= a/tan A
so
b= 21/tan A

but what number do I divide 21 by to get the answer? whats the next step in finding the number I need to solve the problem? I am homeschooled and my teacher only listed up to that step she didnt show us how to solve it. I tried dividing 21 by 45, and also by the square root of 45 but none of the answers are listed. Please help me find the next step.

?2010-07-07T14:12:58Z

Favorite Answer

if A = 45 deg, tanA = 1

b = 21/1 = 1