Question

Evaluate the expressions without using a calculator. \( 4 \tan 330^{\circ} \cos 135^{\circ} \sin 300^{\circ} \)

Ask by Dawson Pearson. in South Africa
Mar 09,2025

Upstudy AI Solution

Tutor-Verified Answer

Answer

The expression evaluates to \( -\sqrt{2} \).

Solution

1. Evaluate \( \tan 330^\circ \): Since \( 330^\circ = 360^\circ - 30^\circ \), we have \[ \tan 330^\circ = \tan(-30^\circ) = -\tan 30^\circ = -\frac{1}{\sqrt{3}}. \] 2. Evaluate \( \cos 135^\circ \): The angle \( 135^\circ \) lies in the second quadrant where cosine is negative. Also, \[ \cos 135^\circ = -\cos 45^\circ = -\frac{\sqrt{2}}{2}. \] 3. Evaluate \( \sin 300^\circ \): Since \( 300^\circ = 360^\circ - 60^\circ \), and sine is negative in the fourth quadrant, \[ \sin 300^\circ = -\sin 60^\circ = -\frac{\sqrt{3}}{2}. \] 4. Substitute the values into the expression: \[ 4 \tan 330^\circ \cos 135^\circ \sin 300^\circ = 4 \left(-\frac{1}{\sqrt{3}}\right) \left(-\frac{\sqrt{2}}{2}\right) \left(-\frac{\sqrt{3}}{2}\right). \] 5. Multiply the factors step by step: - There are three negative signs, so their product is negative. - Multiply the constants: \[ 4 \cdot \frac{1}{\sqrt{3}} \cdot \frac{\sqrt{2}}{2} \cdot \frac{\sqrt{3}}{2} = 4 \cdot \frac{1 \cdot \sqrt{2} \cdot \sqrt{3}}{\sqrt{3} \cdot 4}. \] - Cancel \(\sqrt{3}\) in the numerator and the denominator: \[ = \frac{4 \cdot \sqrt{2}}{4} = \sqrt{2}. \] - Considering the overall negative sign: \[ = -\sqrt{2}. \] Thus, the evaluated expression is \[ -\sqrt{2}. \]

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Beyond the Answer

First, let's evaluate each trigonometric function in the expression. 1. **Finding \( \tan 330^{\circ} \)**: - Since \( 330^{\circ} = 360^{\circ} - 30^{\circ} \), it lies in the fourth quadrant where tangent is negative. - Thus, \( \tan 330^{\circ} = -\tan 30^{\circ} = -\frac{1}{\sqrt{3}} \). 2. **Finding \( \cos 135^{\circ} \)**: - \( 135^{\circ} = 180^{\circ} - 45^{\circ} \) is in the second quadrant where cosine is negative. - Therefore, \( \cos 135^{\circ} = -\cos 45^{\circ} = -\frac{1}{\sqrt{2}} \). 3. **Finding \( \sin 300^{\circ} \)**: - \( 300^{\circ} = 360^{\circ} - 60^{\circ} \) is in the fourth quadrant where sine is negative. - Therefore, \( \sin 300^{\circ} = -\sin 60^{\circ} = -\frac{\sqrt{3}}{2} \). Now, substituting these values into the expression \( 4 \tan 330^{\circ} \cos 135^{\circ} \sin 300^{\circ} \): \[ 4 \left(-\frac{1}{\sqrt{3}}\right) \left(-\frac{1}{\sqrt{2}}\right) \left(-\frac{\sqrt{3}}{2}\right) \] Calculating step-by-step: 1. \( -\frac{1}{\sqrt{3}} \times -\frac{1}{\sqrt{2}} = \frac{1}{\sqrt{3}\sqrt{2}} = \frac{1}{\sqrt{6}} \) 2. However, now we multiply that result with \( -\frac{\sqrt{3}}{2} \): \[ \frac{1}{\sqrt{6}} \times -\frac{\sqrt{3}}{2} = -\frac{\sqrt{3}}{2\sqrt{6}} \] 3. Now, we can simplify this: \(-\frac{\sqrt{3}}{2\sqrt{6}} = -\frac{\sqrt{3}}{2 \cdot \sqrt{6}} = -\frac{\sqrt{3}}{2 \cdot \sqrt{2 \cdot 3}} = -\frac{\sqrt{3}}{2 \cdot \sqrt{2}\cdot \sqrt{3}} = -\frac{1}{2\sqrt{2}} \). 4. Finally, multiply it by 4: \[ 4 \times -\frac{1}{2\sqrt{2}} = -\frac{4}{2\sqrt{2}} = -\frac{2}{\sqrt{2}} = -\sqrt{2} \] Thus, the value of the expression \( 4 \tan 330^{\circ} \cos 135^{\circ} \sin 300^{\circ} \) is: \[ \boxed{-\sqrt{2}} \]

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