Answer:
sin(B)=cos(90-B)
Step-by-step explanation:
sin(B)=cos(90-B) is a co-function identity.
We can also prove it using the difference identity for cosine.
Let's do that:
cos(90-B)
equals
cos(90)cos(B)+sin(90)sin(B)
0cos(B)+1sin(B)
0+sin(B)
sin(B)
Therefore cos(90-B)=sin(B).