Hello, anna12345!
We're expected to know: .
. . and be able to apply it twice.
Multiply top and bottom by
. . .
. .
I have no idea how to prove these. Any solutions would be greatly appreciated.
1)
tan(x+y+z) = (tanx + tany +tanz - tanxtanytanz)/(1- tanxtany- tanxtanz-tanytanz)
2)
sin(pi/2 +x)cos(pi-x)cot(3pi/2+x)=sin(pi/2-x)sin(3pi/2-x)cot(pi/2+x)
3) csc^2(pi/2-x)=1+sin^2xcsc^2(pi/2-x)
Thanks in advance.