Theorem neghalfpire

Description: -u _pi / 2 is real. (Contributed by David A. Wheeler, 8-Dec-2018)

	Ref	Expression
Assertion	neghalfpire	$$⊢-\frac{\mathrm{\pi }}{2}\in ℝ$$

Proof

Step	Hyp	Ref	Expression
1		halfpire	$$⊢\frac{\mathrm{\pi }}{2}\in ℝ$$
2	1	renegcli	$$⊢-\frac{\mathrm{\pi }}{2}\in ℝ$$