# Trig Ratio

Learning how to convert trig ratio is important as it tests on your understanding of simple trigonometry functions. Trig ratio involves finding the basic angle of the trigonometry function and then reducing it to its simpliest form. We shall look closely at how to simplify the trig ratio

Basic angle of is defined as the acute angle between OP and its projection onto the x-axis. By definition, the basic angle is non-negative. In each of the below diagrams, the drawn angle is the basic angle corresponding to the angle .

Below is a simple diagram to help you determine the sign ( positive or negative) of the trig ratio in their respective quadrants. We call this diagram the ‘ASTC' diagram.

With these diagrams and the basis of trig ratio, we can proceed to learn more about trig ratios . You should refer back to these diagrams in the event that you forget the signs or where the basic angles are.

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