Given f(x)=sin2x and g(x)=3cosx
*draw the graph of f and g on the same set of axes for x [0°;180°]
You MUST know the basic shapes of y = sinx and y = cosx
You also must know the effects of a and k for y = asin(kx) and y = acos(kx)
e.g. y = sin(2x) would have 2 complete periods from 0 to 360°, or a period of 360°/2 = 180°
y = 3cosx would have an amplitude of 3 , but a period of 360°
check:
https://www.wolframalpha.com/input/?i=plot+y+%3D+sin%282x%29%2C+y+%3D+3cosx+from+0+to+%CF%80
Just look at the graph of you two functions, ignore the rest of the page.
Notice you got a complete sine curve, since the period was 180°
but only half the cosine curve since your domain was from 0 to 180°