If Tana / 2 = 3, then cosa is

Let Tana / 2 = t
cosa=(1-t^2)/(1+t^2)=(1-9)/(1+9)=-4/5.

RELATED INFORMATIONS

1. Tana / 2 = 1 / 3 for cos (π - a)
2. If Tana = 1 / 2, then what is cos (2a + π / 2), the answer is 45 degrees,
3. Given cos (A-wu / 6) + Sina = 4 / 5 times the root 3, then the value of sin (a + 7 Wu / 6) is?
4. sina=5/13 π/2
5. It is known that sin (a + b) = 33 / 65, CoSb = 5 / 13 Such as the title
6. Let Tana = √ 1-A / A, where 0
7. If 2sina-3cosa = 0, then sin2a=
8. If Tan ^ 2A = 2tan ^ 2B + 1, then cos2a + sin ^ B =?
9. Given Tan ^ 2A = 2tan ^ 2B + 1, what is cos2a + sin ^ 2B? Write out the whole operation process
10. Given Tan & # 178; a = 2tan & # 178; B + 1, then cos2a + Sin & # 178; b =? The finer the process, the better
11. Given a ∈ (0, π), cosa = 1 / 3, then what is Tana?
12. Given Tana = - 3 / 4, find the square of 2 + sinacosa cosa The detailed process is needed. According to the square of sina + the square of cosa = 1, the detailed process solution is obtained, and the detailed and fast additional fraction is obtained
13. Given that a is an acute angle, and Sina cosa / Sina + cosa = 1 / 3, Tana = Sina / cosa, find Tana
14. If Tana = - 2, then the square of Sina - 3 * (the square of COSA) =?
15. Tana = 3 find the square of the following formula (Sina) - 2sinacosa - (COSA) / 4 (COSA) - 3sinacosa
16. If Tana = 1 / 2, what degree is ∠ a equal to
17. Tana = 0.1 A is equal to what degree? Be specific```` Yes + points```
18. Tana = 1 / 3, how many degrees does a equal
19. What is 1 + (Tana) ^ 2 How much is the simplification
20. Sina and cosa are two of the equations 13X square-7x + M = 0, (1). Find the value of Tana (2). 1-tana / cos 2A × (1 + Tana)