An easier way to remember Trigonometry Identities

I’m one who really hates memorizing formulas, be in as a student or tutor. So I shall share how I remember the three very useful trigonometry identities. I’ll start with the one which you all definitely can identify with.

$sin^{2}x + cos^{2}x = 1$

Credits: www.spikedmath.com

Now how do we get the other 2?

Simply divide the above equation by $sin^{2}x$ and $cos^{2}x$ respectively.
Lets divide by $sin^{2}x$ !
$\frac{sin^{2}x}{sin^{2}x} + \frac{cos^{2}x}{sin^{2}x} = \frac{1}{sin^{2}x}$
Voila! we have $1 + cot^{2}x = cosec^{2}x$

You can try to do the same with $cos^{2}x$ ! Let me know if you have problems!

About

KS Teng

KS has been teaching H2/H1 Mathematics and IB mathematics for the more than 10 years. Having taught students from all various Junior Colleges, KS adapts to students' abilities and help them better understand the topics. As someone who loves to teach mathematics and sees it as a truly useful tool in life, KS seeks to enable students to appreciate math. Therefore, his tuition mission is to motivate and cultivate students to be independent and confident thinkers.

An easier way to remember Trigonometry Identities

Now how do we get the other 2?

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