identity

tave/Matlab to plot the main trigonometric functions, thus obtaining fig. 8.

These plots can be obtained as subplots of a same figure by the following Oc-

tave/Matlab script:

s = sin(theta);

c = cos(theta);

t = tan(theta);

subplot(2,2,1); plot(theta,s);

axis([0,4*pi,-1,1]);

grid; title('Sine of an angle');

xlabel('angle [rad]');

ylabel('sin');

% replot; % Octave only

subplot(2,2,2); plot(theta,c);

grid; title('Cosine of an angle');

xlabel('angle [rad]');

ylabel('cos');

% replot; % Octave only

subplot(2,2,3); plot(theta,t);

grid; title('Tangent of an angle');

xlabel('angle [rad]');

ylabel('tan');

axis([0,4*pi,-6,6]);

% replot; % Octave only

codomain of sine and cosine is limited to the interval [-1, 1], while the codomain

of the tangent takes values on all real axis. The tangent approaches infinity for

all the values of the argument that multiples of /2, i.e. in these points we have

vertical asymptotes.