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Description: Deduction adding conjuncts to an equivalence. (Contributed by NM, 8-Sep-2006)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | 3anbi1d.1 | ⊢ ( 𝜑 → ( 𝜓 ↔ 𝜒 ) ) | |
| Assertion | 3anbi2d | ⊢ ( 𝜑 → ( ( 𝜃 ∧ 𝜓 ∧ 𝜏 ) ↔ ( 𝜃 ∧ 𝜒 ∧ 𝜏 ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | 3anbi1d.1 | ⊢ ( 𝜑 → ( 𝜓 ↔ 𝜒 ) ) | |
| 2 | biidd | ⊢ ( 𝜑 → ( 𝜃 ↔ 𝜃 ) ) | |
| 3 | 2 1 | 3anbi12d | ⊢ ( 𝜑 → ( ( 𝜃 ∧ 𝜓 ∧ 𝜏 ) ↔ ( 𝜃 ∧ 𝜒 ∧ 𝜏 ) ) ) |