Find all the solutions of the equation in the interval {o,2pi)

sec^2x+tanx=1

1 answer

One of the basic identities you should have at your disposal is
sec^2 x = 1 + tan^2 x

so sec^2 x + tanx = 1
1 + tan^2 x + tanx = 1
tanx(tanx + 1) = 0
tanx = 0 or tanx = -1

if tanx = 0 then x = 0 or x = 180°
if tanx = -1, then x = 135° or x = 315°

x = 0 , π , 3π/4 , 7π/4