cosine

[jwells]

I have a prolem... how do you find the measure of an angle if you are given the cosine of the angle.

 

[stapel]

Use the inverse cosine.

Eliz.

 

[pka]

If you have a good calculator there should be a function key labeled cos<SUP>-1</SUP>. That is inverse cosine function called the arccosine.
\(\displaystyle \cos (\theta ) = x\quad \Rightarrow \quad \arccos (x) = \theta\).

So enter the value of the cosine, use the cos<SUP>-1</SUP> key
The value you get will be in radians between 0 and pi.

 

[jwells]

The problem is Find the measure of angle H to the nearest degree if cos H = 0.5446. I don't get an answer that can be right. Using the calculator. cos or cos-.

 

[pka]

\(\displaystyle \L
\begin{array}{l}
\cos (\theta ) = 0.5446\quad \Rightarrow \quad \arccos (0.5446) = 0.995 \\
0.995 \approx 57.003^ \circ \\
\end{array}\)

 

[stapel]

I don't get an answer that can be right.

What answer are you getting? How? Why do you believe it to be incorrect?

Please reply with specifics. Thank you.

Eliz.