1. trigo

how to do this:
x=0.7*cos(2*pi*200*t);
y=0.5*cos(2*pi*1000*t);
z=x+y;

2. $\cos(2k\pi)=1,\forall k\in\mathbf{Z}$

3. not help

i need how the way to get one result

4. What is t? Is integer, rational, real?

5. real

x1=07*cos(2*pi*200*t);
x2=07*cos(2*pi*1000*t);

i need toknow how i do x1+x2

6. Originally Posted by jsampaio
i need how the way to get one result
What result? What exactly is your question? Solve for z, solve for t, graph the system, etc.

-Dan

7. Fourier

is for then put that in fourier is because AM signal modulation.

8. Originally Posted by jsampaio
x1=07*cos(2*pi*200*t);
x2=07*cos(2*pi*1000*t);

i need toknow how i do x1+x2
$cos(a) + cos(b) = 2cos \left ( \frac{a + b}{2} \right ) ~ cos \left ( \frac{a - b}{2} \right )$

-Dan