Theorem coshalfpi

Description: The cosine of _pi / 2 is 0. (Contributed by Paul Chapman, 23-Jan-2008)

	Ref	Expression
Assertion	coshalfpi	$$⊢\cos \left(\frac{\mathrm{\pi }}{2}\right)=0$$

Proof

Step	Hyp	Ref	Expression
1		sinhalfpilem	$$⊢\left(\sin \left(\frac{\mathrm{\pi }}{2}\right)=1\wedge \cos \left(\frac{\mathrm{\pi }}{2}\right)=0\right)$$
2	1	simpri	$$⊢\cos \left(\frac{\mathrm{\pi }}{2}\right)=0$$