# CBSE Class 10-Mathematics: Chapter –8 Introduction to Trigonometry Part 9

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**Question 2:**

If , evaluate:

(i)

(ii)

**Answer:**

Consider a triangle ABC in which

Let

Then, using Pythagoras theorem,

(i)

(ii)

**Question 3:**

If , check whether

or not.

**Answer:**

Consider a triangle ABC in which .

And

Let .

Then, using Pythagoras theorem,

And

Now, L.H.S.