Sin and Cos
Plotting the Graph of Sine
The function of sine has the up-down curve which is repeated in every 2π radians or say 360 degrees. It begins with 0 and heads up to 1 by π/2 radians (or 90°) and again goes down to -1 at 270°. The graph returns to zero at 360°.
Plotting the cosine graph
It is like the sine function, but it starts from 1 at 0°, goes to zero at 90°, decreases further to -1 at 180°, rises again to zero at 270°, then back to 1 at 360°.
Plotting the graph of tangent
The function of tangent has a different shape which goes positive and negative infinity, which crosses via 0 and at every 180 degrees, as shown in the graph.
At 90 degrees and at -90 degrees, 270 degrees positive and negative, etc., the function is undefined as it can be positive infinity or negative infinity.