Answer:
x = 6
Step-by-step explanation:
If two secants are drawn frm an external point to a circle, then the product of the measures of one secant's external part (outside) and that entire secant is equal to the product of the measures of the other secant's external part and that entire secant, that is
x(x + 4) = 5(5 + 7) = 5 × 12 = 60
x² + 4x = 60 ( subtract 60 from both sides )
x² + 4x - 60 = 0 ← in standard form
(x + 10)(x - 6) = 0 ← in factored form
equate each factor to zero and solve for x
x + 10 = 0 ⇒ x = - 10
x - 6 = 0 ⇒ x = 6
However, x > 0 , then x = 6