Looking at the original word and its code:
TRAPEZIUM: T-R-A-P-E-Z-I-U-M (9 letters)
RTPAEIZMU: R-T-P-A-E-I-Z-M-U (9 letters)
Comparing position by position:
- Positions 1 and 2: T, R → R, T (swapped)
- Positions 3 and 4: A, P → P, A (swapped)
- Position 5: E → E (unchanged)
- Positions 6 and 7: Z, I → I, Z (swapped)
- Positions 8 and 9: U, M → M, U (swapped)
The pattern swaps consecutive pairs of letters, except the middle letter (position 5) remains unchanged.
Applying this pattern to RECTANGLE:
RECTANGLE: R-E-C-T-A-N-G-L-E (9 letters)
- Positions 1 and 2: R, E → E, R
- Positions 3 and 4: C, T → T, C
- Position 5: A → A
- Positions 6 and 7: N, G → G, N
- Positions 8 and 9: L, E → E, L
Result: E-R-T-C-A-G-N-E-L
Therefore, RECTANGLE is coded as ERTCAGNEL.
The answer is Option 3: ERTCAGNEL