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=