set the to equal:
x^2 - 4x+4 = 2x-4
solve for X
subtract 2x from each side:
x^2 -6x + 4 = -4
subtract 4 from each side:
x^2 -6x = -8
add 8 to both sides:
x^2 -6x +8 = 0
factor the polynomial:
x = 4 and x = 2
using the line equation replace x with 2 and 4 and solve for y
y = 2(2) - 4 = 0
y = 2(4)-4 = 4
so the 2 points the line crosses the curve is (2,0) and (4,4)
using those 2 points you can calculate the length:
distance = sqrt((x2-x1)^2 +(y2-y1)^2
distance = sqrt( (4-2)^2 + (4-0)^2)
distance = sqrt (2^2 + 4^2)
distance = sqrt (4+16)
= sqrt 20
= 2 sqrt(5) EXACT LENGTH