# Obtuse Angled Triangle

## Obtuse Angled triangle definition:

If one of the interior angles of the triangle is obtuse(i.e more than 90°), then the triangle is called the obtuse angle triangle. The obtuse angle in the triangle can be any one of the three angles and the remaining two angles are acute angles.

The obtuse angle triangle properties are different from other triangles. Look at the table below for the same:

 Triangle type Obtuse Acute Right Difference Any One angle more than 90° All angles less than 90° One angle equal to 90°

## Properties of Obtuse Angled Triangle:

Triangle ABC is a perfect example to study the triangle type – Obtuse.

• In triangle ABC, interior angle ACB =37°, which is less than 90°, so it’s an acute angle.
• Interior angle ABC = 96°, which is more than 90° so, it’s an obtuse angle.
• Interior angle BAC=47°, which is less than 90°, so it’s an acute angle.
• As this triangle ABC has one angle (ABC=96 degree) more than 90°, so this triangle is obtuse.

### Obtuse angled triangle formula:

Area = $\frac{1}{2}\times b\times h$

Or

A=$\sqrt{S(S-a)(S-b)(S-c)}$sq.units

Where S = $\frac{a+b+c}{2}$ (s= semiperimeter)

Perimeter = a+b+c

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#### Practise This Question

A quadrilateral in which at least one pair of opposite sides is parallel is known as