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Description: _pi is greater than 3. (Contributed by Brendan Leahy, 21-Aug-2020)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | pigt3 | |- 3 < _pi |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | sincos6thpi | |- ( ( sin ` ( _pi / 6 ) ) = ( 1 / 2 ) /\ ( cos ` ( _pi / 6 ) ) = ( ( sqrt ` 3 ) / 2 ) ) |
|
| 2 | 1 | simpli | |- ( sin ` ( _pi / 6 ) ) = ( 1 / 2 ) |
| 3 | ax-1cn | |- 1 e. CC |
|
| 4 | 2cnne0 | |- ( 2 e. CC /\ 2 =/= 0 ) |
|
| 5 | 3cn | |- 3 e. CC |
|
| 6 | 3ne0 | |- 3 =/= 0 |
|
| 7 | 5 6 | pm3.2i | |- ( 3 e. CC /\ 3 =/= 0 ) |
| 8 | divcan5 | |- ( ( 1 e. CC /\ ( 2 e. CC /\ 2 =/= 0 ) /\ ( 3 e. CC /\ 3 =/= 0 ) ) -> ( ( 3 x. 1 ) / ( 3 x. 2 ) ) = ( 1 / 2 ) ) |
|
| 9 | 3 4 7 8 | mp3an | |- ( ( 3 x. 1 ) / ( 3 x. 2 ) ) = ( 1 / 2 ) |
| 10 | 3t1e3 | |- ( 3 x. 1 ) = 3 |
|
| 11 | 3t2e6 | |- ( 3 x. 2 ) = 6 |
|
| 12 | 10 11 | oveq12i | |- ( ( 3 x. 1 ) / ( 3 x. 2 ) ) = ( 3 / 6 ) |
| 13 | 2 9 12 | 3eqtr2i | |- ( sin ` ( _pi / 6 ) ) = ( 3 / 6 ) |
| 14 | pire | |- _pi e. RR |
|
| 15 | pipos | |- 0 < _pi |
|
| 16 | 14 15 | elrpii | |- _pi e. RR+ |
| 17 | 6re | |- 6 e. RR |
|
| 18 | 6pos | |- 0 < 6 |
|
| 19 | 17 18 | elrpii | |- 6 e. RR+ |
| 20 | rpdivcl | |- ( ( _pi e. RR+ /\ 6 e. RR+ ) -> ( _pi / 6 ) e. RR+ ) |
|
| 21 | 16 19 20 | mp2an | |- ( _pi / 6 ) e. RR+ |
| 22 | sinltx | |- ( ( _pi / 6 ) e. RR+ -> ( sin ` ( _pi / 6 ) ) < ( _pi / 6 ) ) |
|
| 23 | 21 22 | ax-mp | |- ( sin ` ( _pi / 6 ) ) < ( _pi / 6 ) |
| 24 | 13 23 | eqbrtrri | |- ( 3 / 6 ) < ( _pi / 6 ) |
| 25 | 3re | |- 3 e. RR |
|
| 26 | 25 14 17 18 | ltdiv1ii | |- ( 3 < _pi <-> ( 3 / 6 ) < ( _pi / 6 ) ) |
| 27 | 24 26 | mpbir | |- 3 < _pi |