📌 Basic Trigonometric Ratios
sinθ=OppositeHypotenuse,cosθ=AdjacentHypotenuse,tanθ=sinθcosθ\sin \theta = \frac{\text{Opposite}}{\text{Hypotenuse}}, \quad \cos \theta = \frac{\text{Adjacent}}{\text{Hypotenuse}}, \quad \tan \theta = \frac{\sin \theta}{\cos \theta}sinθ=HypotenuseOpposite,cosθ=HypotenuseAdjacent,tanθ=cosθsinθ cscθ=1sinθ,secθ=1cosθ,cotθ=1tanθ\csc \theta = \frac{1}{\sin \theta}, \quad \sec \theta = \frac{1}{\cos \theta}, \quad \cot \theta = \frac{1}{\tan \theta}cscθ=sinθ1,secθ=cosθ1,cotθ=tanθ1
📌 Pythagorean Identities
sin2θ+cos2θ=1\sin^2 \theta + \cos^2 \theta = 1sin2θ+cos2θ=1 1+tan2θ=sec2θ1 + \tan^2 \theta = \sec^2 \theta1+tan2θ=sec2θ 1+cot2θ=csc2θ1 + \cot^2 \theta = \csc^2 \theta1+cot2θ=csc2θ
📌 Angle Transformation
sin(−θ)=−sinθ,cos(−θ)=cosθ\sin(-\theta) = -\sin \theta, \quad \cos(-\theta) = \cos \thetasin(−θ)=−sinθ,cos(−θ)=cosθ tan(−θ)=−tanθ\tan(-\theta) = -\tan \thetatan(−θ)=−tanθ
📌 Standard Angles
| θ | 0° | 30° | 45° | 60° | 90° |
|---|---|---|---|---|---|
| sin θ | 0 | 1/2 | √2/2 | √3/2 | 1 |
| cos θ | 1 | √3/2 | √2/2 | 1/2 | 0 |
| tan θ | 0 | 1/√3 | 1 | √3 | ∞ |
📌 Sum and Difference Formulas
sin(A±B)=sinAcosB±cosAsinB\sin(A \pm B) = \sin A \cos B \pm \cos A \sin Bsin(A±B)=sinAcosB±cosAsinB cos(A±B)=cosAcosB∓sinAsinB\cos(A \pm B) = \cos A \cos B \mp \sin A \sin Bcos(A±B)=cosAcosB∓sinAsinB tan(A±B)=tanA±tanB1∓tanAtanB\tan(A \pm B) = \frac{\tan A \pm \tan B}{1 \mp \tan A \tan B}tan(A±B)=1∓tanAtanBtanA±tanB
📌 Double Angle Formulas
sin2A=2sinAcosA\sin 2A = 2 \sin A \cos Asin2A=2sinAcosA cos2A=cos2A−sin2A=2cos2A−1=1−2sin2A\cos 2A = \cos^2 A - \sin^2 A = 2\cos^2 A - 1 = 1 - 2\sin^2 Acos2A=cos2A−sin2A=2cos2A−1=1−2sin2A tan2A=2tanA1−tan2A\tan 2A = \frac{2\tan A}{1 - \tan^2 A}tan2A=1−tan2A2tanA
📌 Product to Sum Formulas
sinAsinB=12[cos(A−B)−cos(A+B)]\sin A \sin B = \frac{1}{2}[\cos(A - B) - \cos(A + B)]sinAsinB=21[cos(A−B)−cos(A+B)] cosAcosB=12[cos(A−B)+cos(A+B)]\cos A \cos B = \frac{1}{2}[\cos(A - B) + \cos(A + B)]cosAcosB=21[cos(A−B)+cos(A+B)] sinAcosB=12[sin(A+B)+sin(A−B)]\sin A \cos B = \frac{1}{2}[\sin(A + B) + \sin(A - B)]sinAcosB=21[sin(A+B)+sin(A−B)]