Question

If cos a= 12/13 and sin b= 4/5,
then sin(a-b) equals ..............
Anyone willing to help?
I got -.0072 but I'm not sure if I'm correct, please help

Answer 1

well you need to draw the triangles and find the missing sides so you get the right ratio values



then its

sin(a - b) = sin(a)cos(b) - cos(a)sin(b)

= 5/13*3/5 - 12/13*4/5

= 15/65 - 48/65

= - 33/65

I'd leave it as an exact value..