The length of the side DA from secant theorem is; 10
From the cyclic diagram attached;
Since CA = 12.5 and CB = 4.5, it means that;
BA = 12.5 - 4.5 = 8
From the secant theorem, we know that;
The product of the secant and its exterior segment is equal to the square of the tangent segment.
Thus;
Length of DA = √(8 * 12.5)
Length of DA = 10
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