Problem

If $\cos (x)=-\frac{14}{23}$ (in Quadrant-111), find Give exact answers.
\[
\sin \left(\frac{x}{2}\right)=
\]

Answer

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Answer

So, the exact value of \(\sin \left(\frac{x}{2}\right)\) is \(\boxed{-0.8968544062928813}\).

Steps

Step 1 :Given that \(\cos (x)=-\frac{14}{23}\) (in Quadrant-111), we are asked to find the exact value of \(\sin \left(\frac{x}{2}\right)\).

Step 2 :We know that the cosine function is negative in the third quadrant, so the sine function will also be negative in this quadrant.

Step 3 :We can use the half-angle formula for sine, which is \(\sin \left(\frac{x}{2}\right)= \pm \sqrt{\frac{1-\cos(x)}{2}}\). Since we are in the third quadrant, we will use the negative root.

Step 4 :Substituting the given value of \(\cos(x)\) into the formula, we get \(\sin \left(\frac{x}{2}\right)= -\sqrt{\frac{1-(-\frac{14}{23})}{2}}\).

Step 5 :Solving this, we get \(\sin \left(\frac{x}{2}\right)\) to be approximately -0.8968544062928813.

Step 6 :So, the exact value of \(\sin \left(\frac{x}{2}\right)\) is \(\boxed{-0.8968544062928813}\).

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