Question

which expression completes the fundamental trig identity? cos(pi/2 - u)=
a. cos u
b. sin u
c. csc u
d. -sec u

Answer 1

Figure out what cos/sin/csc/-sec will get you.
Remember SOH CAH tOA

Answer 2

OR...
use: cos(A - B) = cosAcosB + sinAsinB

Answer 3

so what would i do using that formula?