Equivalent Trigonometric Expressions

This video lesson discusses equivalent trigonometric expressions including all the cofunction identities. This lesson was created for the MHF4U Advanced Functions course in the province of Ontario, Canada.

[nickysterling]

Still helping people 10 years later, thanks

[funbigmama]

THANK YOU!!! I HAVE BEEN STRESSING OVER THIS FOR SO LONG 

[lolgayvids]

Thank you, We had a supply teacher teaching us, what is said to be the most difficult unit of the year, for the past three weeks, this really helped me to understand what I am suppose to do. Huh, maybe we should move the teaching programs onto the internet. Thank you once again!

[AlRichards]

Probably the most useful situation is to put a trig expression in a simpler form or a more useful form. For example 3sin(X) - 4sin^3(X) is equivalent to sin3X and perhaps in a particular situation sin3(X) might be easier to deal with than 3sin(X) - 4sin^3(X).

[AlRichards]

@AirDJ100 • Have you ever seen the unit circle with the cos and sin of all the special angles listed? If not watch at least the first couple of minutes of my Trigonometric Ratios and Special Angles video. The cofunction identities are relationships between various trig ratios. All the ones in my lesson focus on what a particular trig ratio equals (what other trig ratio is the same) if you add pi/2 to the angle. E.g cos(TT/3) = 1/2 and sin(5TT/6)= 1/2 so sin(x + TT/2) = cos(x) if x = TT/3.

[fiellascriptful]

What would you say are equivalent trig expressions used for?

[AirDJ]

how do you get the co-function identities anyhow?

[MrButtonMonkey]

thanks! every semester you save children's grades

[UlTrAGaMeR]

thanks a lot, it really cleared up some questions I had.

[KevinJames]

how do you know when to use the 1st set (pi/2-x) of cofunction identities shown in the video vs with second set (pi/2 +x) ? 

[whivvy]

how much money have you made off of this video? just curious lol!