Animated Solution for Mathematics - Definite Integration: The area bounded by the curve 4y2=x2(4−x)(x−2) is equal to:
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Visualized Solution
4y2=x2(4−x)(x−2)
Given curve: 4y2=x2(4−x)(x−2)
To find the area, we first identify the domain where y is real.
Domain of y
For y to be real: x2(4−x)(x−2)≥0
Since x2≥0, we must have (4−x)(x−2)≥0
This implies x∈[2,4]
Symmetry about x-axis
The equation is unchanged if y is replaced by −y.
Thus, the curve is symmetric about the x-axis.
Total Area =2× (Area above the x-axis)
Area =2∫24ydx
Area =2∫24ydx
From 4y2=x2(4−x)(x−2), we get y=2x(4−x)(x−2) for y≥0
Area =2∫242x(4−x)(x−2)dx
Expanding the Quadratic
Area =∫24x(4−x)(x−2)dx
Expanding the quadratic: (4−x)(x−2)=−x2+6x−8
Area =∫24x−x2+6x−8dx
Completing the Square
Completing the square: −x2+6x−8=1−(x2−6x+9)=1−(x−3)2
Area =∫24x1−(x−3)2dx
Substitution: x−3=t
Let x−3=t⇒dx=dt
Also, x=t+3
Updating the Limits
When x=2,t=2−3=−1
When x=4,t=4−3=1
Area =∫−11(t+3)1−t2dt
Splitting the Integral
Area =∫−11t1−t2dt+3∫−111−t2dt
Odd Function Property
Let f(t)=t1−t2. Since f(−t)=−f(t), it is an odd function.
∫−11t1−t2dt=0
Even Function Property
g(t)=1−t2 is an even function.
Area =3×2∫011−t2dt=6∫011−t2dt
Standard Integral Formula
Using ∫a2−x2dx=2xa2−x2+2a2sin−1(ax)
Area =6[2t1−t2+21sin−1t]01
Final Area
Area =6[0+21⋅2π]=23π
Final Area=23π
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The Sigma Insight: Area Bounded by Curves
Solution Diagram
Analyzing the Setup
To find the area bounded by the curve 4y2=x2(4−x)(x−2), we must first determine the domain where the curve exists. Since y2 must be non-negative, the expression x2(4−x)(x−2) must be ≥0.
Because x2 is always non-negative, the condition simplifies to (4−x)(x−2)≥0. Testing the intervals, we find that the curve exists only for x∈[2,4].
The Mirror of Symmetry
The presence of y2 in the equation indicates that the curve is symmetric about the x-axis. This allows us to calculate the area of the upper half and multiply by two.
The expression for the upper half is:
y=2x(4−x)(x−2)
The total area A is given by:
A=2∫242x(4−x)(x−2)dx=∫24x(4−x)(x−2)dx
The Art of Completing the Square
We simplify the quadratic expression inside the square root:
(4−x)(x−2)=−x2+6x−8=1−(x2−6x+9)=1−(x−3)2
Substituting this into our integral, we get:
A=∫24x1−(x−3)2dx
We apply the substitution t=x−3, which implies dx=dt. The limits of integration change from [2,4] to [−1,1]:
A=∫−11(t+3)1−t2dt
The Elegance of Odd and Even Functions
We split the integral into two distinct parts:
A=∫−11t1−t2dt+3∫−111−t2dt
The first term, ∫−11t1−t2dt, involves an odd function over a symmetric interval, which evaluates to 0. We are left with the second term:
A=3∫−111−t2dt=6∫011−t2dt
Final Calculation
The integral ∫011−t2dt represents the area of a quarter-circle with radius 1, which is 4π. Alternatively, using the standard integral formula: