# Trigonometry Identities: sin(-x) = - sin(x) and cos(-x) = cos(x)

in MES Science16 days ago (edited)

In this video I prove the two identities, sin(-x) = - sin(x) and cos(-x) = cos(x), which show that cosine is an even function while sine is an odd function.

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# Trigonometry Identities

## sin(-ϴ) = -sin(ϴ) and cos(-ϴ) = cos(ϴ)

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You prove once again that I'm an ignoramus, lol, but when I saw how easily my daughter solves problems in trigonometry, I became part of something bigger than I am :)
I absorb information more easily if I understand how to apply it in real life. How can knowing about the even and odd of these functions help me?
!CTP

haha good to hear you are feeling more inclined to learn mathematics! Math has lots of applications in the real world, but fundamentally it is just a mental exercise of logic. Chess or other similar board games are other good examples of mental workouts, which have indirect benefits to one's mental well being in the same way that lifting heavy rocks (aka physical exercise) has to one's physical well being.

Regarding even and odd functions, unless you are dealing with modeling electromagnetic waves, I'm not sure how they can help you directly. But in terms of the underlying logic, it is just an exercise in pattern recognition, which can indirectly help you notice patterns in your everyday social or work setting.

I absolutely agree with you that this material is highly specialized and is applied mathematics, for application in a certain field of activity, it is not clear why children are tormented by this at school? If they are interested in mathematics, they will love it, like chess, which not everyone loves :)
!WINE

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