Can plz you list the formulae of function change while putting ((pie/2) - x ) like

sin(pie/2 - x) = sin x

cos (pie/2 - x) = - sin x

something like that.

Also, explain it using graph (4 quadrant system,All +ve in 1st quad,Sin +ve in 2 quad,Tin 3rd,Cin 4th quad method)

Means how I use this ASTC for help in these formulae.

Thanks