Solve the following equation given that 0°=?<360°

Question

cosθ - cosθ tanθ=0

Answer 1

          cosθ - cosθ tanθ = 0

 

cosθ - cosθ (sinθ/cosθ) = 0

 

                 cosθ - sinθ = 0

 

                          cosθ = sinθ

 

0°= θ < 360°

 

so θ = 45° or θ = 225°

Answer 2

Let    x=θ

 

Factor out cosx.

 

cosx(1 - tanx) = 0

 

 

Set the factors equal to zero.

 

cosx = 0          and              1 - tanx = 0

 

                                               tanx = 1

 

 Solve for the two parts.

 

x = 90                                     x = 45

x = 270                                   x = 180 + 45 = 245