16. A stone is dropped into a lake, creating a circular ripple that travels outward at a speed of \( 60 \mathrm{~cm} / \mathrm{s} \). Find the rate at which the area within the circle is increasing after (a) 1 s , (b) 3 s , and (c) 5 s . What can you conclude?

\( y = \sqrt { \sin 2 x } \frac { d y } { d x } \)

(17) If \( \overrightarrow{\mathrm{F}_{1}}=5 \overrightarrow{\mathrm{i}}+3 \overrightarrow{\mathrm{j}}, \overrightarrow{\mathrm{F}_{2}}=a \overrightarrow{\mathrm{i}}+6 \vec{j} \) and \( \overrightarrow{\mathrm{F}_{3}}=-14 \overrightarrow{\mathrm{i}}+b \overrightarrow{\mathrm{j}} \) are three forces meeting at one point, \( \overrightarrow{\mathrm{R}}=\left(10 \sqrt{2}, \frac{3}{4} \pi\right) \) then : \( (a, b)=\ldots \ldots \ldots \) \( \begin{array}{llll}\text { (a) }(-1,1) & \text { (b) }(2,1) & \text { (c) }(-1,2) & \text { (d) }(1,-1)\end{array} \)

If the pelecypods were fossilised at start of mudstone deposition. Knowing the relative age of their ini appearance, and if 0.8 m deposition of mudstone represents 1 million years: 3.1.1 What is the approximate age of the contact between C and D? Please give the age in number (and corre unit) as well as the appropriate period (show your workings). 3.1.2 Could fossils identified in 2.1 .1 be found in layer G? Give reasons for your answer? 3.2.1 In what direction is the strata above the unconformity dipping and by how much? 3.2.2 Based on your assessment of your cross-section, and above answers, list the sequence of geological events that took place since the deposition of the unknown layer below A. And provida the timing of some of the events.

б)

rình \( \left\{\begin{array}{l}x+y=9 \\ x-y=-1\end{array}\right. \) là