To find the length of chord CD, we can use the intersecting chords theorem, which states that if two chords AB and CD intersect at point E inside the circle, then:
\[ AE \times EB = CE \times ED \]
Given the segments:
- \( AE = a = 13 \) mm
- \( EB = b = 20 \) mm
- \( CE = c \) (unknown)
- \( ED = d = 10 \) mm
Substituting the known values into the equation:
\[ AE \times EB = CE \times ED \]
This results in:
\[ 13 \times 20 = c \times 10 \] \[ 260 = 10c \] \[ c = \frac{260}{10} \] \[ c = 26 \]
Now that we have \( CE = 26 \) mm, we can find the length of chord CD, which is:
\[ CD = CE + ED = c + d \] \[ CD = 26 + 10 \] \[ CD = 36 \] mm
Therefore, the length of chord CD is 36 mm.
The correct response is: Chord CD is 36 mm.