Area of Triangles
An Area of triangle PQR with vertices P(x1,y1), Q(x2,y2) , and R(x3,y3).
An Area of triangle PQR is denoted by ▲and is given as :
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°.
Stair method To calculate area :
In this method – 1st co-ordinates placed at first row and last row in determinant.
For right arrow use positive (+) sign and for left arrow use negative (-) sign.
- For Triangle –
In triangle PQR has vertices P(x1 , y1) , Q(x2 , y2 ) & R( x3 , y3 )
For Polygon:
The area of polygon with vertices are given as-
(x1 , y1 ) , (x2 , y2 ) , (x3 , y3 ) , … , (xn , yn ) .
