tanA=ntanB

sinA=msinB
find cos^2A in terms of 'm' and 'n'
plz help

1 answer

taking reciprocals, we have
cot^2A = 1/n^2 cot^2B
csc^2A = 1/m^2 csc^2B

m^2 csc^2A - n^2 cot^2A = csc^2B-cot^2B = 1

Now you should be able to get things down to cos^2A