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Sine, cosine and tangent

In a right triangle, sine, cosine and tangent link an angle to the ratio between two sides. Sine is the opposite side divided by the hypotenuse, cosine is the adjacent side divided by the hypotenuse, and tangent is the opposite divided by the adjacent side.

sin⁡v=oppositehypotenuse\sin v = \frac{\text{opposite}}{\text{hypotenuse}}sine
cos⁡v=adjacenthypotenuse\cos v = \frac{\text{adjacent}}{\text{hypotenuse}}cosine
tan⁡v=oppositeadjacent\tan v = \frac{\text{opposite}}{\text{adjacent}}tangent

Symbols

vvangle°

Example

Hypotenuse 10 and v=30∘v = 30^\circ: opposite side =10sin⁡30∘=5= 10\sin 30^\circ = 5 and adjacent side =10cos⁡30∘≈8.66= 10\cos 30^\circ \approx 8.66.

Check that the calculator is in degrees.
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← Equation of the tangent · The sine rule →

Part of Mathematics 1T: Trigonometry.