Answer:
B
Explanation:
Since UV is a tangent then ∠ WUV = 90°
WZ = WU = x - 1 ( both radii of the circle ) , then
WV = x - 1 + 2 = x + 1
Using Pythagoras' identity in the right triangle
WU² + UV² = WV² , that is
(x - 1)² + (2x - 4)² = (x + 1)² ← expand factors using FOIL
x² - 2x + 1 + 4x² - 16x + 16 = x² + 2x + 1
5x² - 18x + 17 = x² + 2x + 1 ← subtract x² + 2x + 1 from both sides
4x² - 20x + 16 = 0 ← divide through by 4
x² - 5x + 4 = 0
(x - 1)(x - 4) = 0 ← in factored form
Equate each factor to zero and solve for x
x - 1 = 0 ⇒ x = 1
x - 4 = 0 ⇒ x = 4
But x ≠ 1 as radius x - 1 = 0
Thus x = 4 → B