# Anonymous

posted by .

study of sunspots. spots in a year min. is 10, max is 110. between max's of 1750 & 1948, 18 cycles occurred. Find a sinusoidal equation to model this.

My equation looks something like this so far:

y=50sin(2pi/11(x-d))+60

so How do I get the phase shift? d? I am confused about what would be x and y to plug into the formula and find d? Because the max occurs at 1750, but what would be the x and y values to sub in and why?

• Anonymous -

y=50sin( 2pi(x-d)/11 )+60
when x = 1750, you have a max and sin (2 pi(1750-d)/11) = 1
or 2 pi (1750-d)/11 = pi/2 (90 degrees for max of sin function)
1750-d =11/4 (in other words a quarter of a cycle after start)
d = 1750 - 11/4

• Anonymous -

How did you get 1750-d=11/4?

• Anonymous -

I mean, so would d = 1747.25
ie
y=50sin(2pi/11(x-1747.25))+60

## Similar Questions

1. ### MAth

If 1 gallon (gal) of water weighs 8.34 pounds (lb), how much does 3.75 gal weigh?
2. ### trig

I have finished the questions for the following, but could someone please check to see if my answers are right because there are no answers for these questions since it's a sheet that my teacher gave us. Ok, just let me know where …
3. ### PreCalc

y =( (C-A)/2 ) sin( (X - (A - ( (C - A)/2 ) ) )( pi/(C-A) ) ) + (B - ( (B-D)/2 ) How do I rearange this for this equation for the all of the variables including A, B, C, D, X were pi is the greek leter pi if you didn't notice this …
4. ### Math

For each of the following quadratics, determine if the equation has a max or a min, determine the value of the max or min, the direction of opening and the vertex. y = -2(x + 3)2 – 4 y = 4(x – 3)2 + 7 y = -x2 y = -½(x + 6)2
5. ### Calculus

Find any absolute max/min and local max/min for the function f(x)=x^3-4x+5 on the interval [0,5). Made sure to prove that these points are max/min values. This is what I did so far. f'(x)=3x^2-4=0 3x^2=4 x= 2/sqrt3 The -2/sqrt3 is …
6. ### math

how to solve this problem: max min(x-y)..... here where the max have written, under it x>=0 is also given. also under min y>=0 is given. Also tell that is this is equals to min max(x-y) ?
7. ### Physics- uncertainty

Eileen, Jackie, and Kathryn needed to find the difference between two angles A1 and A2, that they had drawn on a diagram:  B = A1+A2  They then had to find the cosine of B. Jackie measured A1 to be 50° and A2 to be 3°. But their …
8. ### Math

Find the critical points and the interval on which the given function is increasing or decreasing, and apply the First Derivative Test to each critical point f(x)= (7/4)x^4+(28/3)x^3+(-63/2)x^2-252x critical points in increasing order: …
9. ### Algebra 2

Please help super confused!!! Which points are the best approximation of the relative maximum and minimum of the function?
10. ### Calculus

Consider the differential equation dy/dx = 2x - y. Let y = f(x) be the particular solution to the differential equation with the initial condition f(2) = 3. Does f have a relative min, relative max, or neither at x = 2?

More Similar Questions