In the figure, CD is a tangent to the circle at point D, and CA is a secant intersecting the circle at points B and A. The length of is ______.
Answer & Analysis
Analysis
Question Analysis
The main focus is applying the Secant - Tangent Rule. We know the lengths of segments and of a secant line from an external point to the circle, and is expressed in terms of . We need to find the value of and then the length of .
Key Concept Explanation
Secant - Tangent Rule: If a tangent line and a secant line are drawn from an external point to a circle, with the tangent length , the external part of the secant , and the entire secant length , then . In our case, considering in relation to the secant and its part , we have .
Step - by - Step Solution
1. Set up the equation using the rule:
We know and , and .
According to the Secant - Tangent Rule,
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