To protect a circular area of a park, cameras are placed on a lamppost in the center of the area. If each camera can observe an arc measure of $75^{\circ}$, how many cameras are needed to observe the entire area around the lamppost?

Describe the formation of an oxbow lake.

Let

$$Q \left( x ^ { \prime } , y ^ { \prime } \right)$$

be any point of L' different from

$$P \left( x _ { 1 } , y _ { 1 } \right)$$

Explain why

$$\frac { y ^ { \prime } - y _ { 1 } } { x ^ { \prime } - x _ { 1 } } = m$$

.

Complete each sentence by writing the form of the verb indicated in parentheses.

The art students are _________ pictures of buildings. (present participle of sketch)

Factor. Assume that variables used as exponents represent positive integers.

$$2 x^{2 n}+11 x^n+5$$

The image of a nearby object formed by a camera lens is $(a)$ at the lens' focal point. $(b)$ always blurred. $(c)$ at the same location as the image of an object at infinity. $(d)$ farther from the lens than the lens' focal point.

Find (a) the fourth partial sum and (b) the sum of the infinite series. $\sum_{k=1}^{\infty} \frac{4}{10^{k}}$

Find an equation of the tangent line to the graph of the function at the given point.

$$\begin{matrix} \text{Function} & \text{Point}\\ \text{y=tan x} & \text{}{\left(-\frac{\pi}{4},-1\right)}\\ \end{matrix}$$

Determine a rotation $\mathbf{x}=P \mathbf{x}^{\prime}$ that removes the cross-product terms, and give its equation in the $x^{\prime} y^{\prime} z^{\prime}$-system. Name the quadric.

$$2 x^2+3 y^2+23 z^2+72 x z+150=0$$

The normal melting point of copper is $1357 \mathrm{~K}$, and $\Delta_{\text {fus }} \mathrm{H}$ of $\mathrm{Cu}$ is $13.05 \mathrm{~kJ} \mathrm{~mol}^{-1}$. (a) How much heat, in kilojoules, is evolved when a $3.78 \mathrm{~kg}$ sample of molten Cu freezes?

a. What are two main ways in which soil organisms contribute to soil formation?

b. Give examples of three types of decomposers and describe their effects on soil.

c. What would happen to the fertility of a soil if all decomposers were removed? Explain.

The element cesium (Cs) freezes at $28.4^{\circ} \mathrm{C}$, and its molar enthalpy of fusion is $\Delta H_{\text {fus }}=2.09 \mathrm{~kJ} / \mathrm{mol}$

When molten cesium solidifies to $\mathrm{Cs}(\mathrm{s})$ at its normal melting point, is $\Delta S$ positive or negative?

In the following sentence, underline any incorrect verb form and write the correct form above it. If all the verbs in a sentence are correct, write C after the sentence.

Either I have leaved my keys somewhere, or they have fell out of my pocket.

Give the word derived from Greek and/or Latin elements that matches given of the following. Verify your answer in a medical dictionary. Note that the wording of the dictionary definition may vary from the wording below.
Formation of calculi ________________