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The area (in sq. units) bounded by the parabola y2=16xy^2 = 16x and its latus rectum is

Solution

✅ Correct Option: 4

Given parabola: y2=16xy^2 = 16x

This is a standard parabola opening to the right with form y2=4axy^2 = 4ax.

Comparing: 4a=164a = 16

a=4a = 4

Key points:

  • Vertex = (0,0)(0, 0)
  • Focus = (a,0)=(4,0)(a, 0) = (4, 0)
  • Latus rectum is a vertical line at x=4x = 4

The latus rectum is a vertical line passing through the focus, perpendicular to the axis of symmetry.

For this parabola, latus rectum is the line x=4x = 4

Finding the endpoints by substituting x=4x = 4 in y2=16xy^2 = 16x:

y2=16(4)=64y^2 = 16(4) = 64

y=±8y = \pm 8

The latus rectum goes from (4,−8)(4, -8) to (4,8)(4, 8) with length 16 units.


The area needed is the region between the curved parabola and the straight latus rectum line.

From the parabola: y2=16xy^2 = 16x

y=4xy = 4\sqrt{x} (taking positive value)

Since the parabola is symmetric about the x-axis, the area above the x-axis can be found and multiplied by 2.

Area =2×∫04y dx= 2 \times \int_0^4 y \, dx

Area =2×∫044x dx= 2 \times \int_0^4 4\sqrt{x} \, dx

Area =8∫04x dx= 8 \int_0^4 \sqrt{x} \, dx


∫x dx=∫x1/2 dx\int \sqrt{x} \, dx = \int x^{1/2} \, dx

=x3/23/2= \dfrac{x^{3/2}}{3/2}

=23x3/2= \dfrac{2}{3}x^{3/2}

Area =8×[23x3/2]04= 8 \times \left[\dfrac{2}{3}x^{3/2}\right]_0^4

Area =8×23×[43/2−0]= 8 \times \dfrac{2}{3} \times [4^{3/2} - 0]


43/2=(41/2)34^{3/2} = (4^{1/2})^3

=23= 2^3

=8= 8


Area =8×23×8= 8 \times \dfrac{2}{3} \times 8

=163×8= \dfrac{16}{3} \times 8

=1283= \dfrac{128}{3} sq. units

Therefore, the area bounded by the parabola and its latus rectum is 1283\dfrac{128}{3} square units.

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