what is tan (a-b) when sin a= 4/5 and cos b= 5/13
Undefined, because that is not a right triangle, as 4^2+5^2 does not equal 13^2.
Alex
tan a = 4/3 and tan b = 12/5
And tan(a - b) = [ tan a - tan b] / [ 1 + tan a * tan b ] = [ 4/3 - 12/5 ] / [ 1 - (4/3)(12/5) ] =
([ 20 - 36] / 15) /[ 1 - 48/15] = [-16/15] / [ -33/15] = 16/33
