**Note :**

**a) if an area of a triangle is given then use ± sign.**

**b) if points P, Q & R are collinear , then area of triangle is zero.**

**Condition for three points to be collinear :**

**If the area of triangle is zero then all points must be collinear .**

**Types of Triangle :**

** 1.Equilateral Triangle : all sides are equal**

**2.Isosceles Triangle : two sides are equal**

**3.Right-angled Triangle : two sides are perpendicular i.e one of them angle is 90°.**