Trigonométrie formules usuelles

t = tan A/2
1. tan A = 2t / (1-t²2)
2. cos A = (1 - t²2) / (1 + t²2)
3. sin A = 2t / (1 + t²)
Produits
1. sin A + sin B = 2 sin [(A+B) /2] cos [(A-B) /2]
2. sin A - sin B = 2 cos [(A+B) /2] sin [(A-B) /2]
3. cos A + cos B = 2 cos [(A+B) /2] cos [(A-B) /2]
4. cos A - cosB = - 2 sin [(A+B) /2] sin [(A-B) /2]
Egalités
1. sin² x+ cos²x =1
2. 1 + tan² x = (1/cosx)²
3. 1+cot² x = (1/sinx)²
Sommes
1. sin (A+B) = sin A cos B + cos A sin B
2. cos (A+B) = cos A cos B - sin A sin B
3. tan (A+B) = (tan A+ tan B) / (1 - tanA tanB)
4. sin (A-B) = sin A cos B - cos A sin B
5. cos (A-B) = cos A cos B + sin A sin B
6. tan (A-B) = (tan A - tan B) / (1 + tanA tanB)

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	Created by Low Yee Shen over 9 years ago

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