Coterminal Angles Trigonometry
1. Find two positive coterminal angles of $-135^\circ$.
Coterminal angles differ by multiples of $360^\circ$.
Step 1: Add $360^\circ$ to $-135^\circ$: $$-135^\circ + 360^\circ = 225^\circ$$
Step 2: Add another $360^\circ$ for the second positive coterminal angle: $$225^\circ + 360^\circ = 585^\circ$$
Answer: Two positive coterminal angles are $225^\circ$ and $585^\circ$.
2. Find one negative coterminal angle of $480^\circ$.
Step 1: Subtract $360^\circ$ to get a coterminal angle: $$480^\circ - 360^\circ = 120^\circ$$ (positive)
Step 2: Subtract another $360^\circ$ for a negative coterminal angle: $$120^\circ - 360^\circ = -240^\circ$$
Answer: One negative coterminal angle is $-240^\circ$.
3. Convert $210^\circ$ to radians in simplest fractional form.
Step 1: Use conversion: $$\text{radians} = \text{degrees} \times \frac{\pi}{180}$$
Step 2: Apply conversion: $$210^\circ \times \frac{\pi}{180} = \frac{210\pi}{180} = \frac{7\pi}{6}$$
Answer: $210^\circ = \frac{7\pi}{6}$ radians.
4. Convert $\frac{7\pi}{4}$ radians to degrees.
Step 1: Use conversion: $$\text{degrees} = \text{radians} \times \frac{180}{\pi}$$
Step 2: Apply conversion: $$\frac{7\pi}{4} \times \frac{180}{\pi} = \frac{7 \times 180}{4} = 315^\circ$$
Answer: $\frac{7\pi}{4}$ radians = $315^\circ$.
5. Convert $45^\circ$ and $135^\circ$ to radians, simplify answers.
For $45^\circ$:
$$45^\circ \times \frac{\pi}{180} = \frac{45\pi}{180} = \frac{\pi}{4}$$
For $135^\circ$:
$$135^\circ \times \frac{\pi}{180} = \frac{135\pi}{180} = \frac{3\pi}{4}$$
Answer: $45^\circ = \frac{\pi}{4}$ radians and $135^\circ = \frac{3\pi}{4}$ radians.
6. Convert $\frac{2\pi}{3}$ and $\frac{11\pi}{6}$ radians to degrees.
For $\frac{2\pi}{3}$:
$$\frac{2\pi}{3} \times \frac{180}{\pi} = \frac{2 \times 180}{3} = 120^\circ$$
For $\frac{11\pi}{6}$:
$$\frac{11\pi}{6} \times \frac{180}{\pi} = \frac{11 \times 180}{6} = 330^\circ$$
Answer: $\frac{2\pi}{3} = 120^\circ$ and $\frac{11\pi}{6} = 330^\circ$.
7. In a right triangle, opposite side $= 8$, hypotenuse $= 17$, find $\sin \theta$ and $\csc \theta$.
Step 1: Recall $\sin \theta = \frac{\text{opposite}}{\text{hypotenuse}} = \frac{8}{17}$.
Step 2: $\csc \theta$ is the reciprocal: $$\csc \theta = \frac{1}{\sin \theta} = \frac{17}{8}$$
Answer: $\sin \theta = \frac{8}{17}$ and $\csc \theta = \frac{17}{8}$.
8. Given $\cos \theta = \frac{3}{5}$, calculate $\sec \theta$ and $\tan \theta$.
Step 1: $\sec \theta = \frac{1}{\cos \theta} = \frac{1}{3/5} = \frac{5}{3}$.
Step 2: Use identity $\sin^2 \theta + \cos^2 \theta = 1$
$$\sin \theta = \sqrt{1 - \cos^2 \theta} = \sqrt{1 - \left(\frac{3}{5}\right)^2} = \sqrt{1 - \frac{9}{25}} = \sqrt{\frac{16}{25}} = \frac{4}{5}$$
Step 3: Compute $\tan \theta = \frac{\sin \theta}{\cos \theta} = \frac{4/5}{3/5} = \frac{4}{3}$.
Answer: $\sec \theta = \frac{5}{3}$ and $\tan \theta = \frac{4}{3}$.
9. Given $\tan \theta = 3$ and $\cos \theta = \frac{1}{\sqrt{10}}$, find $\sin \theta$ and $\cot \theta$.
Step 1: Recall $\cot \theta = \frac{1}{\tan \theta} = \frac{1}{3}$.
Step 2: Use identity $\tan \theta = \frac{\sin \theta}{\cos \theta}$ to find $\sin \theta$:
$$\sin \theta = \tan \theta \times \cos \theta = 3 \times \frac{1}{\sqrt{10}} = \frac{3}{\sqrt{10}}$$
Answer: $\sin \theta = \frac{3}{\sqrt{10}}$ and $\cot \theta = \frac{1}{3}$.
10. Given $\tan \theta = \frac{5}{12}$ and $\cos \theta = \frac{12}{13}$, find $\sin \theta$ and $\cot \theta$.
Step 1: $\cot \theta = \frac{1}{\tan \theta} = \frac{12}{5}$.
Step 2: Use $\tan \theta = \frac{\sin \theta}{\cos \theta}$:
$$\sin \theta = \tan \theta \times \cos \theta = \frac{5}{12} \times \frac{12}{13} = \frac{5}{13}$$
Answer: $\sin \theta = \frac{5}{13}$ and $\cot \theta = \frac{12}{5}$.