Question

Find sin(s+t) and (s-t) if cos(s)= 1/5 and sin(t) = 3/5 and s and t are in quadrant 1.

=Sin(s)cos(t) + Cos(s)Sin(t)
=Sin(1/5)Cos(3/5) + Cos(-1/5)Sin(3/5)
= 0.389418

Sin(s-t)
=sin(s)cos(t) - cos(s)sin(t)
=sin(-3/5)cos(1/5) - cos(1/5)sin(3/5)
=Sin-3/5 cos-3/5
= -0.46602

HELP PLEASE!!

Answer 1

no, no. Draw your triangles:

if cos(s) = 1/5, then sin(s) = √24/5 = 2√6/5
if sin(t) = 3/5, then cos(t) = 4/5

sin(s+t) = (2√6/5)(4/5) + (1/5)(3/5) = (8√6+3)/25

and similarly for sin(s-t)

Answer 2

I support steve,he is correct.