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## Main Question or Discussion Point

D = 9 + 3cos[pi(t)/14]

where D meters is the depth of the water above the river bed at time t hours after 12 noon on 7 March 2005, Monday. This means that the depth of water only depends on time.

a) Write down the minimum and maximum depths of the river

b) Find the day and time when the water first reaches its minimum.

please help me with these questions! thanks!

where D meters is the depth of the water above the river bed at time t hours after 12 noon on 7 March 2005, Monday. This means that the depth of water only depends on time.

a) Write down the minimum and maximum depths of the river

b) Find the day and time when the water first reaches its minimum.

please help me with these questions! thanks!