Answer:
x = 2
Explanation:
When 2 secants are drawn from an external point to a circle the following theorem applies
outside × whole = outside × whole, that is
(x + 1)(x + 1 + 11) = (x + 4)(x + 4 + 1) ← simplify
(x + 1)(x + 12) = (x + 4)(x + 5) ← expand factors on both sides
x² + 13x + 12 = x² + 9x + 20 ( subtract x² from both sides )
13x + 12 = 9x + 20 ( subtract 9x from both sides )
4x + 12 = 20 ( subtract 12 from both sides )
4x = 8 ( divide both sides by 4 )
x = 2