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 #3
avatar+23254 
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1)  EF || GH   --->   arc(EH) = arc(FG)   --->   x2 - 2x  =  56 - 3x

                                                                  x2 + x - 56  =  0

                                                               (x + 8)(x - 7)  =  0

                                                                                 x  =  7                      (can't be negative)

    I don't know how to use this value for x to find arc(EPF) because I don't know where P is.

 

2)  Because this is a regular dodecagon, each side is congruent to every other side.

     Since you haven't had any trig, try this:

     Within the regular dodecagon,

     --  Draw the regular hexagon  P1P3P5P7P9P11  (with the center of the circle = O)

          Since it is a regular hexagon, angle(P1OP3)  =  60o      

          OP1  =  OP3 =  P1P3  =  1

     --  Draw the diameter of the circle that goes through P2.

          This bisects angle(P1OP3) and also bisects P1P3  --  call this point X.

    --  P1X · XP3  =  P2X · XP8        (P8 is the other end of the diameter from P2)

         P1X  =  XP3  =  1/2

         Let P2X  =  x   --->   XP8  =  2 - x

 

         P1X · XP3  =  P2X · XP8   --->   (1/2)(1/2)  =  (x)(2 - x)

                                                                     1/4  =  2x - x2

                                                        x2 - 2x - 1/4  =  0

 

          By the quadratic formula:  x  =  ( 2 - sqrt(3) ) / 2

 

       Now, look at triangle P1XP2  --  it is a right triangle with P1P2 the hypotenuse

       Using the Pythagorean Theorem:  (P1P2)2  =  (1/2)2 + ( 2 - sqrt(3) )2   

                    --->   P1P2  =  2 - sqrt(3)

 

To find your answer, you'll need to square this and multiply by 12.

Jun 16, 2020
 #1
avatar+15127 
+1

Ronald is a baseball player.  When he hits a baseball, the height of the ball can be modeled by the following function, where t is the number of seconds after the ball is hit and h(t) is the height of the ball in feet after t seconds.

h(t)=−16t2+90t+4

a)  What is the maximum height that the ball reaches?

b)  How long does it take for the ball to reach its maximum height?

c) How long does it take for the ball to hit the ground?

Round all answers to the nearest tenth of a foot or second.

 

Ronald ist ein Baseballspieler. Wenn er einen Baseball schlägt, kann die Höhe des Balls durch die folgende Funktion modelliert werden, wobei t die Anzahl der Sekunden nach dem Schlagen des Balls und h (t) die Höhe des Balls in Fuß nach t Sekunden ist.
a) Was ist die maximale Höhe, die der Ball erreicht?
b) Wie lange dauert es, bis der Ball seine maximale Höhe erreicht hat?
c) Wie lange dauert es, bis der Ball den Boden berührt?

 

Hello Guest!

 

\(h (t) = - 16t^2 + 90t + 4\)

 

b)

\(h'(t)=-32t+90=0\\ t=2.8125\)

\(2.8\ second\ does\ it\ take\ for\ the\ ball\ to\ reach\ ist\ maximum\ height.\)

 

a)

\(h (t) = - 16t^2 + 90t + 4\\ h (t) = - 16\cdot (2.8125)^2 + 90(2.8125) + 4\\ h(t)=130.5625\\ \color{blue}130.6\ foot\ is\ the\ maximum\ height\ that\ the\ ball\ reaches.\)

 

c)

\(h (t) = - 16t^2 + 90t + 4=0\)

\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\\ x = {-90 \pm \sqrt{90^2-4\cdot (-16)\cdot 4} \over 2\cdot (-16)}\\ x=\frac{-90\pm \sqrt{8356}}{-32}\\ x=5.669\)

\(5.7 \ second\ long\ does\ it\ take\ for\ the\ ball\ to\ hit\ the\ ground.\)

laugh  !

Jun 16, 2020
 #4
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Jun 16, 2020
 #3
avatar+355 
-1
Jun 16, 2020

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