PreCalculus - Trigonometry (21 of 54) Reduction Formula (3 of 4) Add pi/2

In this video I will explain the reduction formula (add pi/2).

[sightcraft]

That was pretty useful and clear, your covering the whole chart of reductions would be appreciated

[lilycorey]

This is so helpful, you explain so well!!

[ScottPalmer-mpwe]

Thanks for the excellent, visual explanation of these concepts.

[joeyborja]

I understand the concepts of vertical triangles in terms of similarity inside a circle. But here, I just hope we could see how the triangles are similar through proof or even just through a reference. Again, thank you for your awesome videos, sir.

[haimbenavraham]

The guy who turns water into wine. And cosine into sine.