# Homework Help: Nast y = RSin(x + a)

1. Sep 13, 2008

### thomas49th

1. The problem statement, all variables and given/known data
The curve:
y = sqrt3cosx + sinx

a) Express the equation of the curve in the form y = RSin(x+a), where R and a are constants, R > 0 and 0 < a < pi/2

2. Relevant equations

3. The attempt at a solution

I dont like these nasty R ones. Can someone walk me through please, point me in the right direction and give me tips :) Thanks :)

2. Sep 13, 2008

### Dick

I don't like them much either, which is why I don't want you walk you through it. Start by expanding sin(x+a)=sin(x)cos(a)+cos(x)sin(a) and equate the two sides.

3. Sep 18, 2008

### thomas49th

well i got it

R = 2 and a = pi/3

so

y = 2Sin(x + pi/3)

How do i find:

i) maxiumum point of the graph?
ii) minium point of the graph?
Thanks

4. Sep 18, 2008

### HallsofIvy

Where is the maximum point of sin(theta)? Where is x+ pi/3 equal to that theta?

Same thing for the minimum.

5. Sep 18, 2008

### thomas49th

well sin moves between -1 and 1, so the maximum is when y = 2 and -2 for minimum?
Right?
Thanks

6. Sep 19, 2008

### Defennder

Yes, that's right.
Do you want to find maximum values of y or the x-coordinate corresponding to the minima or maxima of y?