Show that lobachevsky's basic triangle formulas transform into standard formulas of spherical trigonometry if one replaces the sides a,b,c of the triangle by ia, ib, ic, respectively. Assume that the angle C is a right angle.

Formulas: sinAcot(productb)=sinBcot(producta), cosAcos(productb)cos(productc)...

Formulas: sinAcot(productb)=sinBcot(producta), cosAcos(productb)cos(productc)...