1) tan x tan x/2 =
a. csc x - 1
b. sec x + 1
c. sec x - 1
2) sin(pi/4 + x) - sin(pi/4 - x) =
a. sec x
b. sin x
c. csc x
tan x * tan (x/2) =
tan x * tanx
________ =
1 + sec x
tan^2 x
_______ =
sec^2 x - 1
_________ =
sec x + 1
(sec x + 1) (sec x - 1)
_________________ =
sec x - 1
[sin pi/4 cosx + sinx cos pi/4] - [ sin pi/4 cosx - sinx cos pi/4] =
2 sin x cos pi/4 =
2 sin x * [√ 2 ] / 2 =
√2 * sin x
+53 
