Hi everyone, I think that I have got the first part (a) of this question correct but would appreciate someone checking and pointing me in the right direction as I have a feeling that I am missing something as the question seems too simple to be true.

In triangle ABC, angle A=90 and sec B=2

a/ Find cos B - I have got:

sec B=2

1/cos B=2

1=2cos B

cosB=1/2

b/ Find angles B and C

I've got:

cosB=1/2

B=60,300

can't use B=300 as angles in a triangle = 180 so B=60

180-A-B=C so 180-90-60=C=30