The coordinates of the vertices of a triangle are A(1,3), B(6,10), and C(11,18). Find the perimeter of the triangle when the coordinates are multiplied by 3.

2 answers

The distance between A and B can be calculated using the distance formula:
distance(A,B)=sqrt((xb-xa)^2+(yb-ya)^2)
=sqrt((1-6)^2+(3-10)^2)
=sqrt(25+49)
=sqrt(74)
=8.602 approx.
You can find similarly the distances BC and CA.

Add up the sum AB+BC+CA which is the perimeter of the original triangle.
For the triangle with coordinates 3 times shown, multiply the original perimeter by 3.
Triangle IJK has the coordinates listed :



I (5 , -8) J (10 , -8) K (7 , 4)



Where is J' after a reflection over the y-axis?