The value of cos A if sin...

[Maikasha]

Hi! I've had a horrible math teacher this semester, and I have a huge provincial tomorrow. I'm going over a practice provincial, and found that my teacher never clarified this type of problem with me.


"What is the value of cos A if sin A=0.9659 and angle A is an obtuse angle?"

I know that it should be in quadrant two and be a negative answer, but I honestly don't know how to get the value of cosine A.
Acck!
thanks for your time!

 

[stapel]

Have you covered inverse-trig functions?

Thank you.

Eliz.

 

[Maikasha]

Not that I know of..
Thank you for your response!

 

[mcrae]

just throwing this out there

sinA=0.9659
sin^(-1)A=74.9942
cos74.9942=0.2589

not confident on this though

 

[Maikasha]

just throwing this out there

sinA=0.9659
sin^(-1)A=74.9942
cos74.9942=0.2589

not confident on this though

You are awesome! I get it now. Geez, why didn't the teacher explain that in the first place?
Makes total sense, and that's the correct answer. Many thanks! Just so you know, since it's in quadrant two, it'd be negative.
Yet thanks once again!

 

[mcrae]

your welcome