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Metamath Proof Explorer
Description: The cosine of _pi / 2 is 0. (Contributed by Paul Chapman, 23-Jan-2008)
|
|
Ref |
Expression |
|
Assertion |
coshalfpi |
⊢ ( cos ‘ ( π / 2 ) ) = 0 |
Proof
| Step |
Hyp |
Ref |
Expression |
| 1 |
|
sinhalfpilem |
⊢ ( ( sin ‘ ( π / 2 ) ) = 1 ∧ ( cos ‘ ( π / 2 ) ) = 0 ) |
| 2 |
1
|
simpri |
⊢ ( cos ‘ ( π / 2 ) ) = 0 |