Question 1068900
 please help me (cos x-1)(cos x+1)＝0 
----
Poblem # 2 sin t cos t-cos t=0 
cos(t)(sin(t)-1) = 0
cos(t) = 0 or sin(t) = 1
t = 90 degrees 
-----------------------
problem 3 tan²x +tanx=0 
tan(x)(3tan(x)-1) = 0
tan(x) = 0 or tan(x) = 1/3
x = 0 degrees or x = arctan(1/3) = 18.43 degrees
-----------------------------
problem# 4 sen²x-2senx+1=0
(sin(x)-1)^2 = 0
sin(x) = 1
x = 90 degrees
-------------------- 
problem #5 sen 4x cos x=sen x cos 4x 
tan(4x) = tan(x)
x = 60 degrees
--------------
Cheers,
Stan H.
-------------