So, b (0,2).
Point C( 1, a) is the intersection of a straight line and a hyperbola, the intersection point c is the CD⊥y axis, and the vertical foot is d,
Therefore, CD=| 1|= 1, D(0, a),
Therefore, BD = | a-2 |
The area of △BCD is 1.
1/2 * CD * BD = 1/2 * 1 * | a-2 | = 1
So | a-2 | = 2
Therefore, a 1=4 and a2=0 (irrelevant, omitted).
So, a=4.
Let the analytical formula of hyperbola be: y = k1/x.
When x= 1, y=a=4.
Therefore, k 1=4.
So the analytic formula of hyperbola is y = 4/x.
(2) the point c on the straight line y=kx+2 is (1, 4).
So, 4=k+2.
k=2
So the straight line is y=2x+2.
So, A(- 1, 0)
Let E(0, y).
CD= 1,BD=|4-2|=2,BC=√5
AB=√5
AE=√( 1+y^2),BE=|y-2|
A triangle with vertices e, a, B a and b is similar to △BCD.
So ab 2+AE 2 = be 2.
5+ 1+y^2=(y-2)^2
y=- 1/2
Or ab 2 = AE 2+be 2.
5= 1+y^2+(y-2)^2
Y 1=0, y2=2 (coincident with point B, discarded)
y=0 .
Therefore, point E(0,-1/2) or (0,0).