HW039
Math 2984 - Fall 2017
Intro to Mathematical Problem Solving

TASK: Write a function that shrinks a triangle.

COMMENT: Your function should have the form

        function [ x2, y2 ] = triangle_shrink ( x1, y1, s )
      

• x1 and y1 are the x and y coordinates of the vertices;
• s is a shrink factor, like 0.5 or 0.3;
• x2 and y2 are the coordinates of the shrunken vertices.

To shrink a triangle involves two steps:

• compute xc, yc, the coordinates of the centroid of the triangle;
• for each vertex i,

                x2(i) = xc + s * ( x1(i) - xc )
                y2(i) = yc + s * ( y1(i) - yc )
              

The easiest way to verify your calculation is to use the fill() command to plot your original and shrunken triangles.

INSTRUCTIONS:

        Begin with the function header

          Compute the triangle centroid.

          Create the values of x2 and y2.

          return
        end
      

CHECK: The commands:

        x1 = [ 0, 7, 9 ];
        y1 = [ 6, 1, 3 ];
        [ x2, y2 ] = triangle_shrink ( x1, y1, 0.33 );
        fill ( x1, y1, 'b' )
        hold on
        fill ( x2, y2, 'r' )
      

SUBMIT: Because it's a function, your file should be named "triangle_shrink.m". (I don't need a picture of your shrunken triangle.) Your file should begin with:

        % triangle_shrink.m
        % YOUR NAME
        % This script (describe what it does)