# CBSE Class 10-Mathematics: Chapter – 8 Introduction to Trigonometry Part 4

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**Question 2**:

In adjoining figure, find

**Answer**:

Using Pythagoras theorem,

**Question3**:

If , calculate and .

**Answer**

Given: A triangle ABC in which

Let

Then, Using Pythagoras theorem,

**Question4**:

Given , find .

**Answer**:

Given: A triangle ABC in which

Let

Then using Pythagoras theorem,

**Question5**:

If are acute angles such that , then show that .

**Answer**:

In right triangle ABC,

But

[Angles opposite to equal sides are equal]