某天午夜后 小时,港口的水位高度可以通过公式 来建模,其中 。
- (a)
给出潮汐的最大和最小水位。
- (b)
潮汐周期从高潮开始,到下一次高潮结束。已知 24 小时内有 2 个潮汐周期,证明 。
- (c)
当潮汐水位高于 2 m 时,船只可以进入港口。求在第一个 12 小时的周期内,船只可以进入港口的时间范围。
它不会直接告诉你答案,而是问你卡在哪一步看看 AI 是怎么陪你一步步弄懂这道题的
完整解法
6(a)
1. Find the maximum level of the tide
The maximum value of is .
Maximum level m
2. Find the minimum level of the tide
The minimum value of is .
Minimum level m
Maximum level = m, Minimum level = m
6(b)
1. Determine the period of one tide cycle in hours.
Since there are 2 tide cycles in 24 hours, the period of one cycle is:
2. Relate the period to the coefficient of $t$ in the sine function and solve for $k$.
The period of is . Here, .
Shown that .
6(c)
1. Set up the inequality for the height of the water
We require .
2. Find the basic angle and the boundary values for the angle
Let . We solve for .
Basic angle rad.
Since is negative, is in the 3rd and 4th quadrants:
rad
rad
3. Solve for $t$ and state the range of times
For :
For :
From the sine graph, when and .
Thus, the range of times is and .
and
AI 分析,可能出错
用 AI 批改,圈出写错的那一步,并自动将你的薄弱点存入错题本,形成你的错因库。