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# How to memorize Pythagoras' Theorem & Trigonometry

A theorem that we applied on the right angled triangle is called Pythagoras' theorem. The Pythagoras' theorem is named after a great Greek Mathematician - Pythagoras.

Referring to diagram 1 (assuming angle *x* is between side b & side c), side a is Opposite line, side b is adjacent which side c is hypotenuse. The relation between opposite, adjacent and hypotenuse is called * Pythagorean relation* where :

**c ^{2} = a^{2} + b^{2 } or (hypotenuse)^{2} = (Opposite)^{2} + (Adjacent)^{2}**

Pythagoras' theorem can be applied when we study Trigonometry. Referring to diagram 2 (assuming angle *x *is between b & c) , therefore c is hypotenuse, a is opposite and b is adjacent.

To determine the *sine x, cosine x and tangent x*, we applied the formula as below :

*Sine x* = Opposite / Hypotenuse

*Cosine x *= Adjacent / Hypotenuse

*Tangent x* = Opposite / Adjacent

Tips to memorize these three important formula, one can use the terms as below :

**SOH , CAH , TOA**

SOH = Sine, Opposite & Hypotenuse

CAH = Cosine, Adjacent & Hypotenuse

TOA = Tangent, Opposite & Adjacent

I found these tips are useful for me when I was studying Trigonometry last time, hopefully it is useful too to all the readers here..