Question

MATLAB please make it simple to understand

P4.2.5 Write a script that draws an equilateral triangle that is partitioned into four smaller equilateral

triangles by connecting the midpoints of its sides. The four little triangles should be colored

differently.

Answer 1

MATLAB CODE :

%Let's make an equilateral triangle of side 2 with vertices as A(0,0),B(0,2) and C(sqrt(3),1)
V = [0 0; 2 0 ;1 sqrt(3)]; %defining vertices
plot([V(1,1),V(2,1)], [V(1,2),V(2,2)], 'Color', 'k');
hold on
plot([V(2,1),V(3,1)], [V(2,2),V(3,2)], 'Color', 'k');
hold on
plot([V(3,1),V(1,1)], [V(3,2),V(1,2)], 'Color', 'k');
% We'll join the midpoints of each line, coordinates of midpoint of each line
v = [ 1 0 ; 0.5 sqrt(3)/2; 1.5 sqrt(3)/2]; %[1 0 ;% 1*cos 60 1* sin 60; 2 - 1*cos 60 1*sin60]
plot([v(1,1),v(2,1)], [v(1,2),v(2,2)], 'Color', 'k');
hold on
plot([v(2,1),v(3,1)], [v(2,2),v(3,2)], 'Color', 'k');
hold on
plot([v(3,1),v(1,1)], [v(3,2),v(1,2)], 'Color', 'k');
% Using vertices of all 4 triangles, we can fill the triangle with patch command;
% 1st triangle
x1 = [ 0 0.5 1];
y1 = [ 0 sqrt(3)/2 0];
patch(x1,y1,'g')
%2nd triangle
x2 = [ 0.5 1 1.5];
y2 = [ sqrt(3)/2 sqrt(3) sqrt(3)/2];
patch(x2,y2,'b')
%3rd triangle
x3 = [ 1.5 2 1];
y3 = [ sqrt(3)/2 0 0];
patch(x3,y3,'r')
% 4th triangle
x4 = [ 1 0.5 1.5];
y4 = [ 0 sqrt(3)/2 sqrt(3)/2];
patch(x4,y4,'y')

Result: