Study Online and Download Notes of Mathematics 9th Unit 13: Sides and Angles of a Triangle. Recall that if two sides of a triangle are equal, then the angles apposite to them are also equal and vice-versa.

Study Online and Download Notes of

**Mathematics 9th Unit 13: Sides and Angles of a Triangle**. Recall that if two sides of a triangle are equal, then the angles apposite to them are also equal and vice-versa. But in this unit we shall study some interesting inequality relations among sides and angles of a triangle.

After studying this unit, the students will be able to:

- prove that if two sides of a triangle are unequal in length, the longer side has an angle of greater measure opposite to it.
- prove that if two angles of a triangle are unequal in measure, the side opposite to the greater angle is longer than the side opposite to the smaller angle.
- prove that the sum of the lengths of any two sides of a triangle is greater than the length of the third side.
- prove that from a point, out-side a line, the perpendicular is the shortest distance from the point on the line.

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