[问答题]
A water truck tank which is 3 metres lo
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mvql:l87rwz3r segment. The tank is divided into two equal parts and is partially filled with water as shown in the following diagram of the cross-section. The centre of the circle is O , the angle AOB is $\alpha$ radians, and the angle AOF is $\beta$ radians.
1. Given that $\alpha=\frac{\pi}{4}$ , calculate the amount of water, in litres, in the right part of the water tank. Give your answer correct to the nearest integer.
2. Find an expression for the volume of water V , in $ \mathrm{m}^{3}$ , in the left part of the water tank in terms of $\beta$ .
he left part of the tank is now being filled with water at a constant rate of 0.001 $\mathrm{~m}^{3}$ per second.
3. Calculate $\frac{\mathrm{d} \beta}{\mathrm{d} t}$ when $\beta=\frac{3 \pi}{5} $. Round your answer to 3 significant figures.
4. Calculate the amount of time it will take for the left part of the tank to be fully filled with water. Give your answer in minutes and correct to the nearest integer.
