Question

Find the area of triangle formed by joining the mid points of the sides of the triangle whose

Vertices are (0,-1), (2,1) and (0,3).

• A. 1 sq.unit
• B. 2 sq.unit
• C. 3 sq.unit
• D. 4 sq.unit

Answer 1

The correct option is A

1 sq.unit

Let the midpoint of sides AB,BC and CA is D, E and F respectively.

Coordinates of Point D

D = $(\frac{0+2}{2},\frac{-1+1}{2}),D(1,0)$

Similarly point E $(\frac{2+0}{2},\frac{1+3}{2}),E(1,2)$

Co-ordinates of point F $(\frac{0+0}{2},\frac{3-1}{2}),F(0,1)$

Area of triangle DEF = $\frac{1}{2}|1(2-1)+1(1-0)+0(0-2)$

= $\frac{1}{2}(1+1)=1\text{sq unit}$.