Evaluating cos[1/2(arcsin(15/17))]

[GrandMa5TR]

Evaluating cos[1/2(arcsin(15/17))]

I keep working through it but I don't see any identities I can use with the 1/2 half there. Anybody know how to solve this?

 

[mmm4444bot]

I keep working through it but I don't see any identities I can use with the 1/2 half there. Anybody know how to solve this?

Did you read the forum guidelines? You agreed to follow them, when you joined this forum.

Please read the guidelines, and provide the requested information (i.e., show us what you tried).

Thank you for your cooperation. :cool:

 

[Deleted member 4993]

I keep working through it but I don't see any identities I can use with the 1/2 half there. Anybody know how to solve this?

cos(Θ) = 2*[cos(Θ/2)]^2 - 1

 

[GrandMa5TR]

cos(Θ) = 2*[cos(Θ/2)]^2 - 1

I think there actually looking for an answer in radians. Sorry for the confusion.

 

[Deleted member 4993]

I keep working through it but I don't see any identities I can use with the 1/2 half there. Anybody know how to solve this?

sin^-1(15/17) = Θ

sin(Θ) = 15/17

cos(Θ) = ±√(64/289) = ± 8/17

Continue....

 

[Deleted member 4993]

I think there actually looking for an answer in radians. Sorry for the confusion.

The answer CANNOT be in radians.