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diketahui cosx=34\cos x=\frac{3}{4}, maka nilai dari sinx2\sin \frac{x}{2} adalah

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Q. diketahui cosx=34\cos x=\frac{3}{4}, maka nilai dari sinx2\sin \frac{x}{2} adalah
  1. Use Half-Angle Identity: We know that cos(x)=34\cos(x) = \frac{3}{4}. To find sin(x2)\sin(\frac{x}{2}), we can use the half-angle identity for sine, which is sin(x2)=±(1cos(x)2)\sin(\frac{x}{2}) = \pm\sqrt{(\frac{1 - \cos(x)}{2})}. We need to determine the sign (positive or negative) based on the quadrant in which xx lies. However, since we are not given the quadrant, we will assume xx is in a quadrant where sine is positive.
  2. Plug in cos(x): First, we plug the value of cos(x)\cos(x) into the half-angle identity for sine: sin(x2)=±(1cos(x)2)=±(1342)\sin(\frac{x}{2}) = \pm\sqrt{(\frac{1 - \cos(x)}{2})} = \pm\sqrt{(\frac{1 - \frac{3}{4}}{2})}.
  3. Simplify Expression: Now, we simplify the expression inside the square root: (134)=14(1 - \frac{3}{4}) = \frac{1}{4}. So, sin(x2)=±(14/2)\sin(\frac{x}{2}) = \pm\sqrt{(\frac{1}{4}/2)}.
  4. Take Square Root: Next, we simplify the fraction inside the square root: (14)/2=18(\frac{1}{4})/2 = \frac{1}{8}. Therefore, sin(x2)=±18\sin(\frac{x}{2}) = \pm\sqrt{\frac{1}{8}}.
  5. Rationalize Denominator: We take the square root of 18\frac{1}{8}: 18=18=18\sqrt{\frac{1}{8}} = \frac{\sqrt{1}}{\sqrt{8}} = \frac{1}{\sqrt{8}}. To rationalize the denominator, we multiply the numerator and the denominator by 8\sqrt{8}: 18×88=88\frac{1}{\sqrt{8}} \times \frac{\sqrt{8}}{\sqrt{8}} = \frac{\sqrt{8}}{8}.
  6. Simplify 8\sqrt{8}: We simplify 8\sqrt{8} to 222\sqrt{2}, because 8=42=42=22\sqrt{8} = \sqrt{4\cdot2} = \sqrt{4} \cdot \sqrt{2} = 2\sqrt{2}. So, sin(x2)=±(228)\sin\left(\frac{x}{2}\right) = \pm\left(\frac{2\sqrt{2}}{8}\right).
  7. Final Simplification: Finally, we simplify the fraction 228\frac{2\sqrt{2}}{8} by dividing both the numerator and the denominator by 22: sin(x2)=±(24)\sin\left(\frac{x}{2}\right) = \pm\left(\frac{\sqrt{2}}{4}\right).