case h
x✝ : ℝ
⊢ sin (↑x✝ + ↑(π / 2)) = cos ↑x✝
θ : Angle
⊢ sin (θ + ↑(π / 2)) = cos θ
induction θ using Real.Angle.induction_on
no goals
case h
x✝ : ℝ
⊢ sin (↑x✝ + ↑(π / 2)) = cos ↑x✝
exact Real.sin_add_pi_div_two _