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The angle θ1\theta_1 is located in Quadrant III\text{III}, and cos(θ1)=58\cos(\theta_1)=-\dfrac{5}{8} . What is the value of sin(θ1)\sin(\theta_1)? Express your answer exactly. sin(θ1)=\sin(\theta_1)=

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Q. The angle θ1\theta_1 is located in Quadrant III\text{III}, and cos(θ1)=58\cos(\theta_1)=-\dfrac{5}{8} . What is the value of sin(θ1)\sin(\theta_1)? Express your answer exactly. sin(θ1)=\sin(\theta_1)=
  1. Identify Quadrant and Cosine: Identify the quadrant and cosine value.\newlineθ1\theta_1 is in Quadrant III, so cos(θ1)=58\cos(\theta_1) = -\dfrac{5}{8}.
  2. Use Pythagorean Identity: Use the Pythagorean identity: sin2(θ1)+cos2(θ1)=1\sin^2(\theta_1) + \cos^2(\theta_1) = 1.\newlinecos2(θ1)=(58)2=2564\cos^2(\theta_1) = \left(-\dfrac{5}{8}\right)^2 = \dfrac{25}{64}.
  3. Calculate Sin Squared: Calculate sin2(θ1)\sin^2(\theta_1).\newlinesin2(θ1)=1cos2(θ1)=12564=64642564=3964\sin^2(\theta_1) = 1 - \cos^2(\theta_1) = 1 - \dfrac{25}{64} = \dfrac{64}{64} - \dfrac{25}{64} = \dfrac{39}{64}.
  4. Find Sin: Find sin(θ1)\sin(\theta_1).\newlinesin(θ1)=±3964=±398\sin(\theta_1) = \pm\sqrt{\dfrac{39}{64}} = \pm\dfrac{\sqrt{39}}{8}.
  5. Determine Sign: Determine the sign of sin(θ1)\sin(\theta_1) in Quadrant III.\newlineIn Quadrant III, sin(θ1)\sin(\theta_1) is negative, so sin(θ1)=398\sin(\theta_1) = -\dfrac{\sqrt{39}}{8}.

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