Trigonometric Formulas (a) tanθ = sin θ/ cos θ (b) tanθ = 1 /cotθ (c) tanθ.cotθ =1 (d) cotθ =cos θ/ sin θ (e) cosecθ = 1/ sin θ (f) secθ = 1/ cos θ Trigonometric identities (a) sin2 θ =cos θ2 /1 (b) 1/tan2 θ= sec θ2 (c) 1/cot2 θ =cosec θ2