Question
Tue June 12, 2012 By: Ridham Arora

graph of sinx+cosx

Expert Reply
Mon June 18, 2012
sin x + cos x = sqrt(2)* sin(x+45)
 
Now, let see how to plot the graph of sinx + cosx
 
Step1: Get the zero points of the curve.
 
i.e sin x + cos x=0
sinx = -cosx
x = 3pi/4, 7pi/4,....
 
Step2: Putting zeroes in the function, I will get f(x) = sinx + cos x=1 and putting x = 2pi f(x) =1. Thus those are the end points.
 
Step 3: Get the points where the curve is either maxima or minima,
Differentiating, we get
cosx-sinx=0
cosx=sinx
thus, x = pi/4, 5pi/4
 
All the points would be the domian of the function f(x), since it is defined everywhere.
 
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