Trigonometric equation is an equation involving one or more trigonometric ratios of unknown angles. It is expressed as ratios of sine(sin), cosine(cos), tangent(tan), cotangent(cot), secant(sec), cosecant(cosec) angles. For example, cos2 x + 5 sin x = 0 is a trigonometric equation. All possible values which satisfy the given trigonometric equation are called solutions of the given trigonometric equation.
A list of trigonometric equations and their solutions are given below:
Trigonometrical equations | General Solutions |
sin θ = 0 | θ = nπ |
cos θ = 0 | θ = (nπ + π/2) |
cos θ = 0 | θ = nπ |
sin θ = 1 | θ = (2nπ + π/2) = (4n+1) π/2 |
cos θ = 1 | θ = 2nπ |
sin θ = sin α | θ = nπ + (-1)n α, where α ∈ [-π/2, π/2] |
cos θ = cos α | θ = 2nπ ± α, where α ∈ (0, π] |
tan θ = tan α | θ = nπ + α, where α ∈ (-π/2, π/2] |
sin 2θ = sin 2α | θ = nπ ± α |
cos 2θ = cos 2α | θ = nπ ± α |
tan 2θ = tan 2α | θ = nπ ± α |