Unit- | Introduction To Trigonometry | Class-09



Trigonometry deals with right angled triangles. So, we must be clear about the Pythagoras theorem first.

Pythagoras theorem states that, " the square of the length of the hypotenuse is equal to the sum of squares of the lengths of other two sides of the right-angled triangle. 

This also as basic be can concept is of pythagoras theorem which written as:
h2 = p2 + b2

Now, we know the basics of Pythagoras theorem. So we can move ahead to learn how to recognize hypotenuse, perpendicular and the base.

Always in a right angled triangle, the opposite side to the right angle will be the hypotenuse (h). And the side opposite to the reference angle will be the perpendicular(p). Finally the remaining side will be our base (b).

Let's understand this relation with some figures.

From the above-mentioned three figures, I hope we have cleared our concept regarding the hypotenuse, perpendicular and the base of the right angled triangle. Now, we are good to dive in the Trigonometric Ratios.

Trigonometric Ratios:

Let us consider 'Θ' be the reference angle. Now,
We have six trigonometric functions. Here, let us discuss the trigonometric ratios:

Some additional ratios with proof are as follows:

These are 14 important trigonometric ratios. We can form more ratios by using these ratios too. But one can easily understand the other ratios if you have basic understanding of this.

This is much for today's blog. Practice these proof questions time and again and if you have any further questions, feel free to ask me in the comment section below.


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