Answer to Question #6299 in Algebra for Brandy

Question

Solve 3 cos θ = cos θ - √2 for 0 <= θ < 2π

Answer 1

3 cos θ = cos θ - √2 ; 0 <= θ < 2π
2 cos θ = - √2

cos θ = - √2 / 2 then, taking in account that 0 <= θ < 2π

θ = 3π / 4 or θ = 5π / 4