Answer:
x = 21 units
Step-by-step explanation:
<em>The tangent squared is equal to the secant's total length multiplied by the secant's length without the part inside the circle.</em>
So here, that will look like: <em>36² = 27 * (27 + x)</em>
Expansion and multiplication gives us: <em>1296 = 729 + 27x</em>
Subtract from both sides: <em>567 = 27x</em>
Divide from both sides: x = 21.