solve for x tan2x secx 1 0 for x E 0 2pi A 0 2pi3 4pi3 B 0
solve for x tan2x + secx -1 = 0 for x E [0, 2pi)
A) 0, 2pi/3, 4pi/3
B) 0, pi / 3 , 4pi / 3
C.) 2pi / 3 , 4pi / 3, 2pi
Solution
tan^2x + secx -1 = 0
use the identity: 1+tan^2x = sec^2x
So, sec^2x +secx -2 =0
sec^2x +2secx -secx -2 =0
secx( secx +2) -1(secx +2) =0
(secx -1)(secx +2) = 0
secx =1 ----> cosx =1
x= 0, 2pi
secx =-2
cosx = -1/2
x = pi-pi/3 ,pi +pi/3 = 2pi/3 , 4pi/3
x = 2pi/3, 4pi/3
Solution : x= 0, 2pi/3, 4pi/3 , 2pi
Opition A and C
