TS EAMCET 5 May 2018 Shift 1 Solved Paper

Consider the figure,
The equation of the circle is given as,
x2+y2−2x−4y−20=0
The equation of the tangent at (1,7) is,
(1)x+7y−(x+1)−2(y+7) −20=0
y=7
The equation of the tangent at (4,-2) is,
4x−2y−(x+4)−2(y−2)−20=0
3x−2y=20
since, the tangent y=7 and 3x−2y=20 intersect at C. So, the coordinate of C(16,7)
The length of BC is calculated as,
BC=√(16−1)2+(7−7)2
=15
The length of CD is calculated as,
CD=√(16−4)2+(7+2)2
=15
The area of ABCD is calculated as,
Area=

1

2

×15×5+

1

2

×15×5
=75