F.4 Maths

let the coordinates of C and D be (c,0) and (0,d).
Since C is the mid-point of BD,
[-3 +d] /2 = 0, d =3
[4 + 0]/2 = c , c =2
∴ the coordinates of C and D be (2,0) and and D be (0,3).

b1
let AB : BC = r : s, then
[s(7) + r(2)]/(r+s) = 4
7s + 2r = 4r +4s
3s = 2r
r : s = 3:2
AB : BC = 3 : 2
b2
[2(a) + 3(0)]/(2+3) = -3
2a = -15, a = -15/2
the value of a = -15/2