Compute the dot product of the vectors \( u \) and \( v \), and find the angle between the vectors. \( u=\langle-12,0,5\rangle \) and \( \mathbf{v}=\langle 1,2,3\rangle \). \( \mathbf{u} \cdot \mathbf{v}=3 \). (Type an integer or a simplified fraction.) Find the magnitude of the vectors. \( |\mathbf{u}|=13 \) and \( |\mathbf{v}|=\sqrt{14} \) (Type exact answers, using radicals as needed.) The angle between the vectors is \( \square^{\circ} \). (Type your answer in degrees. Do not round until the final answer. Then round to the nearest hundredth as needed.)
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To compute the dot product of the vectors \( \mathbf{u} \) and \( \mathbf{v} \), we use the formula: \[ \mathbf{u} \cdot \mathbf{v} = u_1 v_1 + u_2 v_2 + u_3 v_3 \] Substituting the values: \[ \mathbf{u} \cdot \mathbf{v} = (-12)(1) + (0)(2) + (5)(3) = -12 + 0 + 15 = 3 \] Now, to find the angle \( \theta \) between the vectors, we can use the formula: \[ \cos(\theta) = \frac{\mathbf{u} \cdot \mathbf{v}}{|\mathbf{u}| |\mathbf{v}|} \] We already know \( \mathbf{u} \cdot \mathbf{v} = 3 \), \( |\mathbf{u}| = 13 \), and \( |\mathbf{v}| = \sqrt{14} \). Therefore, \[ \cos(\theta) = \frac{3}{13 \cdot \sqrt{14}} \] Now we can find \( \theta \): \[ \theta = \cos^{-1}\left(\frac{3}{13\sqrt{14}}\right) \] Using a calculator to evaluate \( \theta \): First, compute \( 13\sqrt{14} \): \[ 13\sqrt{14} \approx 13 \times 3.741657 = 48.632561 \] So, \[ \cos(\theta) \approx \frac{3}{48.632561} \approx 0.061674 \] Now take the inverse cosine: \[ \theta \approx \cos^{-1}(0.061674) \] Calculating this gives approximately: \[ \theta \approx 86.45^{\circ} \] Thus, the angle between the vectors is \( \boxed{86.45^{\circ}} \).