11. MODELING WITH MATHEMATICS The lowest frequency of sounds that can be heard by humans is 20 hertz. The maximum pressure \( P \) produced from a sound with a frequency of 20 hertz is 0.02 millipascal. Write and graph a sine model that gives the pressure \( P \) as a function of the time \( t \) (in seconds). (See Example 1. .)

ind \( \tan ^{-1}(-\sqrt{3}) \)

\( \left. \begin{array} { l }{ 40 ^ { \circ } 12 ^ { \prime } 48 ^ { \prime \prime } } \\ { + 17 ^ { \circ } \quad 5 ^ { \prime } 59 ^ { \prime \prime } } \end{array} \right. \)

5. \( \frac{\sin \theta}{\cos \theta}= \) ? 5. \( \sin ^{2} \theta+\cos ^{2} \theta= \) ?

3. Prove \( \sin 3 x=3 \cos ^{2} x \sin x-\sin ^{2} x \) 4. Prove \( \sec 2 x=\frac{\csc ^{2} x}{\csc ^{2} x-2} \) 5. Prove \( \frac{1+\cos \theta}{\sin \theta}+\frac{\sin \theta}{1+\cos \theta}=2 \csc \theta \) 6. Prove \( \frac{c s c^{2} \theta-1}{c s^{2} \theta}=\cos ^{2} \theta \) 7. Prove \( \frac{1}{1-\cos ^{2}}+\frac{1}{1+\cos \mathrm{B}}=2 \csc ^{2} \) 8. Prove \( \left(\cot ^{2} A+1\right)\left(\sin ^{2} A-1\right)=-\cot ^{2} A \)

For what values of the angle between \( \vec{A} \) and \( \vec{B} \) will the dot product \( \vec{A} \vec{B} \) be positive, negative or zero?