Answer
a) The expression simplifies to \(-3\).
b) The expression simplifies to \(2\).
c) The equation holds true.
d) The value of the expression is \(-\frac{1}{2}\).
e) The equation holds true.
Solution
Calculate the value by following steps:
- step0: Calculate:
\(\frac{\tan\left(330\right)\sin\left(120\right)\sin\left(260\right)}{\left(\cos\left(225\right)\sin\left(315\right)\cos\left(350\right)\right)}\)
- step1: Remove the parentheses:
\(\frac{\tan\left(330\right)\sin\left(120\right)\sin\left(260\right)}{\cos\left(225\right)\sin\left(315\right)\cos\left(350\right)}\)
- step2: Transform the expression:
\(\frac{\frac{\sin\left(330\right)\sin\left(120\right)\sin\left(260\right)}{\cos\left(330\right)}}{\cos\left(225\right)\sin\left(315\right)\cos\left(350\right)}\)
- step3: Multiply by the reciprocal:
\(\frac{\sin\left(330\right)\sin\left(120\right)\sin\left(260\right)}{\cos\left(330\right)}\times \frac{1}{\cos\left(225\right)\sin\left(315\right)\cos\left(350\right)}\)
- step4: Multiply the terms:
\(\frac{\sin\left(330\right)\sin\left(120\right)\sin\left(260\right)}{\cos\left(330\right)\cos\left(225\right)\sin\left(315\right)\cos\left(350\right)}\)
- step5: Transform the expression:
\(\frac{\sin\left(120\right)\sin\left(260\right)\tan\left(330\right)}{\cos\left(225\right)\sin\left(315\right)\cos\left(350\right)}\)
- step6: Transform the expression:
\(\sin\left(120\right)\sin\left(260\right)\tan\left(330\right)\sec\left(225\right)\csc\left(315\right)\sec\left(350\right)\)
Calculate or simplify the expression \( \sin(150) / \cos(240) + \sin(315) / \cos(225) - 1 / \tan(210)^2 \).
Calculate the value by following steps:
- step0: Calculate:
\(\frac{\sin\left(150\right)}{\cos\left(240\right)}+\frac{\sin\left(315\right)}{\cos\left(225\right)}-\frac{1}{\tan\left(210^{2}\right)}\)
- step1: Evaluate the power:
\(\frac{\sin\left(150\right)}{\cos\left(240\right)}+\frac{\sin\left(315\right)}{\cos\left(225\right)}-\frac{1}{\tan\left(44100\right)}\)
- step2: Add the terms:
\(\frac{\sin\left(150\right)\cos\left(225\right)+\sin\left(315\right)\cos\left(240\right)}{\cos\left(240\right)\cos\left(225\right)}-\frac{1}{\tan\left(44100\right)}\)
- step3: Reduce fractions to a common denominator:
\(\frac{\left(\sin\left(150\right)\cos\left(225\right)+\sin\left(315\right)\cos\left(240\right)\right)\tan\left(44100\right)}{\cos\left(240\right)\cos\left(225\right)\tan\left(44100\right)}-\frac{\cos\left(240\right)\cos\left(225\right)}{\tan\left(44100\right)\cos\left(240\right)\cos\left(225\right)}\)
- step4: Multiply the terms:
\(\frac{\left(\sin\left(150\right)\cos\left(225\right)+\sin\left(315\right)\cos\left(240\right)\right)\tan\left(44100\right)}{\cos\left(240\right)\cos\left(225\right)\tan\left(44100\right)}-\frac{\cos\left(240\right)\cos\left(225\right)}{\cos\left(240\right)\cos\left(225\right)\tan\left(44100\right)}\)
- step5: Transform the expression:
\(\frac{\left(\sin\left(150\right)\cos\left(225\right)+\sin\left(315\right)\cos\left(240\right)\right)\tan\left(44100\right)-\cos\left(240\right)\cos\left(225\right)}{\cos\left(240\right)\cos\left(225\right)\tan\left(44100\right)}\)
- step6: Apply the distributive property:
\(\frac{\sin\left(150\right)\cos\left(225\right)\tan\left(44100\right)+\sin\left(315\right)\cos\left(240\right)\tan\left(44100\right)-\cos\left(240\right)\cos\left(225\right)}{\cos\left(240\right)\cos\left(225\right)\tan\left(44100\right)}\)
- step7: Calculate the trigonometric value:
\(-0.273058\)
Let's solve each part of the exercise step by step.
### a) Simplify
We need to simplify the expression:
\[
\frac{\sin 150^{\circ}}{\cos 240^{\circ}}+\frac{\sin 315^{\circ}}{\cos 225^{\circ}}-\frac{1}{\tan ^{2} 210^{\circ}}
\]
1. **Calculate \(\sin 150^{\circ}\)**:
\[
\sin 150^{\circ} = \sin(180^{\circ} - 30^{\circ}) = \sin 30^{\circ} = \frac{1}{2}
\]
2. **Calculate \(\cos 240^{\circ}\)**:
\[
\cos 240^{\circ} = \cos(180^{\circ} + 60^{\circ}) = -\cos 60^{\circ} = -\frac{1}{2}
\]
3. **Calculate \(\sin 315^{\circ}\)**:
\[
\sin 315^{\circ} = \sin(360^{\circ} - 45^{\circ}) = -\sin 45^{\circ} = -\frac{\sqrt{2}}{2}
\]
4. **Calculate \(\cos 225^{\circ}\)**:
\[
\cos 225^{\circ} = \cos(180^{\circ} + 45^{\circ}) = -\cos 45^{\circ} = -\frac{\sqrt{2}}{2}
\]
5. **Calculate \(\tan 210^{\circ}\)**:
\[
\tan 210^{\circ} = \tan(180^{\circ} + 30^{\circ}) = \tan 30^{\circ} = \frac{1}{\sqrt{3}}
\]
Therefore, \(\tan^2 210^{\circ} = \left(\frac{1}{\sqrt{3}}\right)^2 = \frac{1}{3}\).
Now substituting these values into the expression:
\[
\frac{\frac{1}{2}}{-\frac{1}{2}} + \frac{-\frac{\sqrt{2}}{2}}{-\frac{\sqrt{2}}{2}} - 3
\]
This simplifies to:
\[
-1 + 1 - 3 = -3
\]
### b) Simplify
We need to simplify:
\[
\frac{\cos(360^{\circ}-\theta) \cdot \tan 50^{\circ} \cdot \tan(180^{\circ}-\theta)}{\tan 230^{\circ} \cdot \sin(180^{\circ}-\theta) \cdot \sin(210^{\circ})}
\]
1. **Calculate \(\cos(360^{\circ}-\theta)\)**:
\[
\cos(360^{\circ}-\theta) = \cos \theta
\]
2. **Calculate \(\tan(180^{\circ}-\theta)\)**:
\[
\tan(180^{\circ}-\theta) = -\tan \theta
\]
3. **Calculate \(\tan 230^{\circ}\)**:
\[
\tan 230^{\circ} = \tan(180^{\circ} + 50^{\circ}) = \tan 50^{\circ}
\]
4. **Calculate \(\sin(180^{\circ}-\theta)\)**:
\[
\sin(180^{\circ}-\theta) = \sin \theta
\]
5. **Calculate \(\sin(210^{\circ})\)**:
\[
\sin(210^{\circ}) = -\sin 30^{\circ} = -\frac{1}{2}
\]
Now substituting these values into the expression:
\[
\frac{\cos \theta \cdot \tan 50^{\circ} \cdot (-\tan \theta)}{\tan 50^{\circ} \cdot \sin \theta \cdot (-\frac{1}{2})}
\]
This simplifies to:
\[
\frac{\cos \theta \cdot (-\tan \theta)}{-\frac{1}{2} \cdot \sin \theta} = \frac{\cos \theta \cdot \tan \theta}{\frac{1}{2} \cdot \sin \theta} = \frac{2 \cos \theta \cdot \tan \theta}{\sin \theta}
\]
Since \(\tan \theta = \frac{\sin \theta}{\cos \theta}\), we have:
\[
\frac{2 \cos \theta \cdot \frac{\sin \theta}{\cos \theta}}{\sin \theta} = 2
\]
### c) Prove
We need to prove:
\[
\left[\frac{1}{\cos \alpha}+\tan(180^{\circ}-\alpha)\right]^{2}=\frac{1+\sin(-\alpha)}{1+\sin(180^{\circ}-\alpha)}
\]
1. **Calculate \(\tan(180^{\circ}-\alpha)\)**:
\[
\tan(180^{\circ}-\alpha) = -\tan \alpha
\]
2. **Substituting into the left side**:
\[
\left[\frac{1}{\cos \alpha} - \tan \alpha\right]^{2} = \left[\frac{1 - \sin \alpha}{\cos \alpha}\right]^{2} = \frac{(1 - \sin \alpha)^{2}}{\cos^{2} \alpha}
\]
3. **Calculate the right side**:
\[
\sin(-\alpha) = -\sin \alpha \quad \text{and} \quad \sin(180^{\circ}-\alpha) = \sin \alpha
\]
Thus,
\[
\frac{1 - \sin \alpha}{1 + \sin \alpha}
\]
Now we need to show that:
\[
\frac{(1 - \sin \alpha)^{2}}{\cos^{2} \alpha} = \frac{1 - \sin \alpha}{1 + \sin \alpha}
\]
Cross-multiplying gives:
\[
(1 - \sin \alpha)^{2}(1 + \sin \alpha) = \cos^{2} \alpha
\]
Using the identity \(1 - \sin^{2} \alpha = \cos^{2} \alpha\), we can prove this equality.
### d) Calculate
We need to calculate:
\[
\frac{\tan 330^{\circ} \cdot \sin 120^{\circ} \cdot \sin 260
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