Step-by-step explanation:
We know that tan=sin/cos, so tan(x+π/2)=

Then, we know that sin(u+v)=sin(u)cos(v)+cos(u)sin(v),
so our equation is then
Then, cos(u+v)=cos(u)cos(v)-sin(u)sin(v), so our expression is then

3/4 is bigger than 2/5. Hope that helps
This is your perfect answer
Answer:
Part a)
Part b) 
Part c) (s+t) lie on Quadrant IV
Step-by-step explanation:
[Part a) Find sin(s+t)
we know that

step 1
Find sin(s)

we have

substitute




---> is positive because s lie on II Quadrant
step 2
Find cos(t)

we have

substitute




is negative because t lie on II Quadrant
step 3
Find sin(s+t)

we have



substitute the values



Part b) Find tan(s+t)
we know that
tex]tan(s + t) = (tan(s) + tan(t))/(1 - tan(s)tan(t))[/tex]
we have



step 1
Find tan(s)

substitute

step 2
Find tan(t)

substitute

step 3
Find tan(s+t)

substitute the values




Part c) Quadrant of s+t
we know that
----> (s+t) could be in III or IV quadrant
----> (s+t) could be in III or IV quadrant
Find the value of cos(s+t)

we have



substitute



we have that
-----> (s+t) could be in I or IV quadrant
----> (s+t) could be in III or IV quadrant
----> (s+t) could be in III or IV quadrant
therefore
(s+t) lie on Quadrant IV