☑️ Very Important formula 1. (α+в)²= α²+2αв+в² 2. (α+в)²= (α-в)²+4αв 3. (α-в)²= α²-2αв+в²        4. (α-в)²= (α+в)²-4αв 5. α² + в²= (α+в)² - 2αв. 6. α² + в²= (α-в)² + 2αв. 7. α²-в² =(α + в)(α - в) 8. 2(α² + в²) = (α+ в)² + (α - в)² 9. 4αв = (α + в)² -(α-в)² 10. αв ={(α+в)/2}²-{(α-в)/2}² 11. (α + в + ¢)² = α² + в² + ¢² + 2(αв + в¢ + ¢α) 12. (α + в)³ = α³ + 3α²в + 3αв² + в³ 13. (α + в)³ = α³ + в³ + 3αв(α + в) 14. (α-в)³=α³-3α²в+3αв²-в³ 15. α³ + в³ = (α + в) (α² -αв + в²) 16. α³ + в³ = (α+ в)³ -3αв(α+ в) 17. α³ -в³ = (α -в) (α² + αв + в²) 18. α³ -в³ = (α-в)³ + 3αв(α-в) ѕιη0° =0 ѕιη30° = 1/2 ѕιη45° = 1/√2 ѕιη60° = √3/2 ѕιη90° = 1 ➡️ ¢σѕ ιѕ σρρσѕιтє σƒ ѕιη тαη0° = 0 тαη30° = 1/√3 тαη45° = 1 тαη60° = √3 тαη90° = ∞ ➡️ ¢σт ιѕ σρρσѕιтє σƒ тαη ѕє¢0° = 1 ѕє¢30° = 2/√3 ѕє¢45° = √2 ѕє¢60° = 2 ѕє¢90° = ∞ ➡️ ¢σѕє¢ ιѕ σρρσѕιтє σƒ ѕє¢ 1. ѕιη2α = 2ѕιηα¢σѕα 2. ¢σѕ2α = ¢σѕ²α − ѕιη²α 3. ¢σѕ2α = 2¢σѕ²α − 1 4. ¢σѕ2α = 1 − ѕιη²α 5. 2ѕιη²α = 1 − ¢σѕ2α 6. 1 + ѕιη2α = (ѕιηα + ¢σѕα)² 7. 1 − ѕιη2α = (ѕιηα − ¢σѕα)² 8. тαη2α = 2тαηα / (1 − тαη²α) 9. ѕιη2α = 2тαηα / (1 + тαη²α) 10. ¢σѕ2α = (1 − тαη²α) / (1 + тαη²α) 11. 4ѕιη³α = 3ѕιηα − ѕιη3α 12. 4¢σѕ³α = 3¢σѕα + ¢σѕ3α » ѕιη²Θ+¢σѕ²Θ=1 » ѕє¢²Θ-тαη²Θ=1 » ¢σѕє¢²Θ-¢σт²Θ=1 » ѕιηΘ=1/¢σѕє¢Θ » ¢σѕє¢Θ=1/ѕιηΘ » ¢σѕΘ=1/ѕє¢Θ » ѕє¢Θ=1/¢σѕΘ » тαηΘ=1/¢σтΘ » ¢σтΘ=1/тαηΘ » тαηΘ=ѕιηΘ/¢σѕΘ