Trigonometry! Some of you may have been practicing trigonometry since 8th grade.. But who really likes trigonometry?

Trigonometry is simple logic and once you get the hang of it, it is a very interesting topic in math! And easy, too!

We all know the basics:

*sinA = perpendicular/hypotenuse*

*cosA = base/hypotenuse*

*tanA = sinA/cosA*

*Â Â Â Â Â Â = perpendicular/base*

*cotA = 1/tanA*

*Â Â Â Â Â Â = cosA/sinA*

*Â Â Â Â Â Â = base/perpendicular*

*sinA = 1/cosecA*

*cosA = 1/secA*

*tanA = 1/cotA*

Trigonometric Table

Here are the important trigonometric identities you’ll need to memorize (YES, MEMORIZE!):

*sin*^{2}A + cos^{2}A = 1

*1 + tan*^{2}A = sec^{2}A

*Â Â Â Â Â Â Â Â Â Â Â Â Â Â ***To remember this identity, s and t are different letters.**

*1 + cot *^{2}A = cosec^{2}A

* Â Â Â Â Â Â Â Â Â Â ***Â To remember this identity, c** (cosec) **and cÂ **(cot)Â **are the same letters and cot is the inverse of tan.**

While solving Proving sums in Trigonometry,

**Remember:**

**If you get a question like this:**

P.T. (1+cosA)/(1 – cosA) = (cosecA + cotA)^{2}

**Observe that the RHS has cosecA=1/sinA and cotA=cosA/sinA**

Since both cosecA and cotA, when simplified have sinA as the denominator, if we **divide EACH TERM on the LHS by sinA**, we will solve the sum.

You can also apply the same technique to proving sums which have **cosA as the denominator**.

Give it a try!

**Hereâ€™s a link to the PDF file for the above notes:**

NOTES – Trigonometric Identities and Tips to Remember

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