SOLUTION: A rectangle is inscribed in a circle of radius 6 ​(see the​ figure). Let P=(x,y) be the point in quadrant I that is a vertex of the rectangle and is on the circle. Answer th

Algebra ->  Points-lines-and-rays -> SOLUTION: A rectangle is inscribed in a circle of radius 6 ​(see the​ figure). Let P=(x,y) be the point in quadrant I that is a vertex of the rectangle and is on the circle. Answer th      Log On


   



Question 1146559: A rectangle is inscribed in a circle of radius 6 ​(see the​ figure). Let P=(x,y) be the point in quadrant I that is a vertex of the rectangle and is on the circle.
Answer the following questions.
​(a) Express the area A of the rectangle as a function of x.
i got the answer 4x(squareroot(36-x^2)
b. Express the perimeter p of the rectangle as a function of x.
i got the answer 4(x+squareroot(36-x^2)
c. Graph A equals​A(x). For what value of x is A​ largest?
how do i graph it so i can get the answer.

Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
Take your value for part (a) which is

matrix%281%2C3%2CA%28x%29%2C%22%22=%22%22%2C4x%2Asqrt%2836-x%5E2%29%29

We could take the derivative of that and set that derivative equal
to 0.  However that would be very time-consuming.  It would be much
easier to square both sides and find the value of x that maximizes
the value of the SQUARE of the area A, because if A² is the largest 
it can be, then A is also the largest it can b.

matrix%281%2C4%2CLet%2CS%28x%29%2C%22%22=%22%22%2C%28A%28x%29%5E%22%22%29%5E2%29



We find the y value when x=3√3:




So the area is greatest when the inscribed rectangle is a square, when
the upper right hand corner is the point P(3√2, 3√2).
(The 0 value is when the area is least, when the rectangle degenerates
into just a line segment, whose area is 0 because its width is 0)



I think this is the graph your teacher wants.  But if he/she wants
the graph of 
matrix%281%2C3%2CA%28x%29%2C%22%22=%22%22%2C4x%2Asqrt%2836-x%5E2%29%29, 
then it is the graph below whose maximum point is (3√2, 72).  To 
plot it, you can only substitute values x=0 through 6.


 
Edwin