Let T be the tangent to the ellipse E : x 2 + 4 y 2 = 5 at the point P ( 1 , 1 ) . If the area of the region…

Let T be the tangent to the ellipse E:x2+4y2=5 at the point P(1,1). If the area of the region bounded by the tangent T, ellipse E, lines x=1 and x=5 is α5+β+γcos-115, then |α+β+γ| is equal to______.

Solution

We have,

x2+4y2=5

x25+y254=1

Tangent at P1,1 to the ellipse is

x+4y=5
Required Area

=155-x4-5-x22dx

=5x4-x28-x45-x2-54sin-1x515

=554-58-54·π2-54+18+12+54sin-115

=554-54-54·π2+54π2-cos-115

=554-54-5π8+5π8-54cos-115

=545-54-54cos-115

So,

α=54, β=-54 & γ=-54

α+β+γ=1.25

Asked in: JEE Main 2021 (20 Jul Shift 1)

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