Answer:
Option A,C,D
Explanation:
Here, α=3sin−(611)
and β=3cos−1(49)4 as 611>12
⇒ sin−1(611)>sin−1(12)=π6
∴ α=3sin−1(611)>π2⇒cosα<0
Now, β=3cos−1(49)
As 49<12⇒cos−1(49)>cos−1(12)=π3
∴ β=3cos−1(49)>π
∴ cosβ<0 and sinβ<0
Now, α+β is slightly greater than 3π2
∴ cos(α+β)>0