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 Mar 16, 2020
 #1
avatar+25889 
+2

First one:    2 pi  is one complete revolution

            6x = 2pi

              x = pi/3 = 3.1415/3 = ~1.047 sec

 

Second one:

   this is a cosine function with a multiplier in front of  -11   

          the cos function USUALLY ranges from -1 to 1....the  -11 makes it range from -11 to 11

              BUT the wave is also shifted  UP by 28 units    so it ranges from  17  to  39   

        the first minimum (17) occurs when?

           -11 cos (pix/48 - 5pi/12) + 28   = 17       subtract 28 from both sides and then divide by -11

                 cos(pix/48 - 5pi/12)  = 1                    arcos both sides

                    pix / 48 - 5pi/12 = 0

                       x = 20 minutes       8:00 + 20 mins = 8:20     

 

   You should be able to do similar for the first maximum.... cheeky

 Mar 16, 2020
edited by ElectricPavlov  Mar 16, 2020

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