Trigonometry formulas 📚

1. Sin x = opposite side ÷ hypotenuse 
2. Cos x = Adjacent side ÷ hypotenuse 
3. Tan x = opposite side ÷ adjacent side
4. Cot x = Adjacent side ÷ opposite side 
   
5. Sec x = hypotenuse ÷ opposite side 
6. Cosec x= hypotenus ÷ adjacent side 
7. Sin x × Cosec x = 1
8. Sin x = 1 ÷ cosec x
9. Cosec x = 1 ÷ sin x
10. Cos x × sec x = 1
11. Cos x = 1 ÷ sec x
12. Sec x = 1 ÷ cos x
13. Sin² x + cos² x = 1
14. Cos x + tan x = 1
15. 1 + cot x = cosec²x 
16. Sin(A +B) = sinA.cosB + cosA.sinB
17. Sin(A-B) = sinA.cosB - cosA.sinB
18. Cos(A+B) = cosA.cosB - sinA.sinB
19. Cos(A-B) = cosA.cosB + sinA.sinB
20. Tan(A+B) = tanA + tanB ÷ 1- tanA.tanB
21. Tan(A-B) = tanA - tanB ÷ 1+ tanA.tanB
22. Sin2x = 2sinx.cosx
23. Sin2x = 2tanx ÷ 1+ tan²x
24. Cos2x = cos²x - sin²x
25. Cos2x = 1 - 2sin²x
26. Cos2x = 2cos²x - 1
27. Tan2x = 2tanx ÷ 1- tan²x
28. Sin3x = 3sinx - 4sin³x
29. Cos3x = 4cos³x - 3cosx
30. Tan3x = 3tanx - tan³x ÷ 1- 3tan²x
31. 1 + cos2x = 2cos²x
32. 1 - cos2x = 2sin²x
33. SinC + sinD = 2sin(C+D ÷ 2). Cos( C - D ÷ 2)
34. SinC - sinD = 2cos(C+D ÷ 2). Sin( C - D ÷ 2)
35. CosC + cosD = 2cos(C+D ÷ 2). Cos( C - D ÷ 2)
36. CosC - cosD = -2sin(C+D ÷ 2).sin( C - D ÷ 2)
37. 2sinA.cosB = sin(A+B) + sin(A-B)
38. 2cosA.sinB = sin(A+B) - sin(A-B)
39. 2cosA.cosB = cos(A+B) + cos(A-B)
40. 2sinA.sinB = cos(A-B) - cos(A+B)