Answer:
(a) y = 3x + 2; (b) (0,2); (c) y = 3x - 8; (d) (2,-2)
(e) Area of ∆ABC = 30; (f) Area of ABCD = 40
Step-by-step explanation:
(a) Equation of AD
(i) Slope of AB
m₁ = (y₂ - y₁)/(x₂ - x₁) = (6 - 8)/(8 - 2)= -2/6 = -⅓
(ii) Slope of AD
m₂ = 3
(ii) y-intercept
y = 3x + b
8 = 3(2) + b= 6 + b
b = 2
The equation of AD is y = 3x + 2.
(b) Coordinates of D
The coordinates of D are (0,2).
(c) Equation of perpendicular bisector of AB
(i) Mid-points of AB
x = ½(x₂ + x₁) = ½(8 + 2) = ½(14) = 5
y = ½(y₂ + y₁) = ½(6 + 8) = ½(14) = 7
The coordinates of the mid-point are (5,7).
Slope = 3
y = mx + b
7 = 3(5) + b = 15 + b
b = 7 - 15 = -8
The equation of the perpendicular bisector is y = 3x - 8.
(d) Coordinates of C
C is at the intersection of BC and the perpendicular bisector of AD.
y = 3x - 8
3y = 4x - 14
3y = 9x - 24
0 = 5x - 10
5x = 10
x = 2
y = 3(2) - 8 = 6 - 8 = -2
The coordinates of C are (2,-2).
(e) Area of ∆ABC
A = ½bh = ½ × 10 × 6 = 30
(f) Area of ABCD
Area of ∆ACD = ½bh = ½ × 10 × 2 = 10
Area of ABCD = ∆ACD + ∆ABC =10 + 30 = 40
