Solve the equation on the interval 0 lessthanorequalto theta

By zero factor theorem :

tant = -1
sect = 1

tan(t) = -1 :
Lets first do tan(t) = 1 --> t= pi/4

We know that tan is negative in quads 2 and 4

So, quad2 angle = pi - pi/4 = 3pi/4
Quad 4 angle = 2pi - pi/4 = 7pi/4

sect = 1
Clearly only one solution, t = 0

So, we have :

0 , 3pi/4 , 7pi/4